Build invoicing app: app/index.html and app/config.yml

Static single-page invoice app per spec. Features:
- Multilingual UI (EN/DE/FR/NO) loaded from config.yml; form always
  prints in the default language
- Sender fields + invoice details (date, project code, invoice no.)
  persisted in localStorage; invoice number auto-increments after
  each generation
- Predefined charge-to recipients selectable from config, or manual entry
- Dynamic invoice line items: predefined products with UOM/price
  pre-fill, free-text fallback, foreign-currency sub-row with
  exchange-rate and per-item price that calculates back to local currency
- Subtotal / tax (configurable rates) / paid / to-pay calculated live
- "Generate Invoice" renders a clean A4-formatted preview overlay;
  "Print / Save as PDF" triggers browser print-to-PDF

https://claude.ai/code/session_015iyCBgoTXNNqaErR287U1u

app/config.yml

@@ -0,0 +1,416 @@
+# Invoice App Configuration
+# (C) 2026 Kristian Benestad. Licensed under the Apache 2 license.
+
+# ── Default language ───────────────────────────────────────────────────────────
+default-code: en
+default-name: English
+default-direction: ltr
+
+# ── Available languages ────────────────────────────────────────────────────────
+languages:
+  - code: en
+    name: English
+    direction: ltr
+  - code: de
+    name: Deutsch
+    direction: ltr
+  - code: fr
+    name: Français
+    direction: ltr
+  - code: "no"
+    name: Norsk
+    direction: ltr
+
+# ── Tax / VAT options ──────────────────────────────────────────────────────────
+tax-rates:
+  - label-en: "No Tax (0%)"
+    label-de: "Keine Steuer (0%)"
+    label-fr: "Sans taxe (0%)"
+    label-no: "Ingen mva (0%)"
+    rate: 0
+  - label-en: "VAT 5%"
+    label-de: "MwSt. 5%"
+    label-fr: "TVA 5%"
+    label-no: "Mva 5%"
+    rate: 5
+  - label-en: "VAT 10%"
+    label-de: "MwSt. 10%"
+    label-fr: "TVA 10%"
+    label-no: "Mva 10%"
+    rate: 10
+  - label-en: "VAT 20%"
+    label-de: "MwSt. 20%"
+    label-fr: "TVA 20%"
+    label-no: "Mva 20%"
+    rate: 20
+  - label-en: "VAT 25%"
+    label-de: "MwSt. 25%"
+    label-fr: "TVA 25%"
+    label-no: "Mva 25%"
+    rate: 25
+
+# ── Units of measure ──────────────────────────────────────────────────────────
+uom:
+  - code: EA
+    labels:
+      en: Each
+      de: Stück
+      fr: Pièce
+      "no": Stykk
+  - code: HR
+    labels:
+      en: Hour
+      de: Stunde
+      fr: Heure
+      "no": Time
+  - code: DY
+    labels:
+      en: Day
+      de: Tag
+      fr: Jour
+      "no": Dag
+  - code: WK
+    labels:
+      en: Week
+      de: Woche
+      fr: Semaine
+      "no": Uke
+  - code: MO
+    labels:
+      en: Month
+      de: Monat
+      fr: Mois
+      "no": Måned
+  - code: LS
+    labels:
+      en: Lump Sum
+      de: Pauschale
+      fr: Forfait
+      "no": Engangsbeløp
+
+# ── Predefined recipients (charge-to) ─────────────────────────────────────────
+charge-to:
+  - display: Acme Corporation
+    name: Acme Corporation Ltd.
+    address1: 123 Business Avenue
+    address2: Suite 400
+    address3: New York, NY 10001
+    address4: ""
+    country: US
+    phone: "+1-212-555-0100"
+    email: accounts@acmecorp.example
+    vat-id: "US-EIN-12-3456789"
+  - display: Example NGO
+    name: Example Non-Profit Organisation
+    address1: 45 Charity Lane
+    address2: London EC1A 1BB
+    address3: ""
+    address4: ""
+    country: GB
+    phone: "+44 20 7123 4567"
+    email: finance@examplengo.example
+    vat-id: "GB123456789"
+
+# ── Project codes ──────────────────────────────────────────────────────────────
+project-codes:
+  - Project 100
+  - Project 110
+  - Project 230
+
+# ── Predefined products / services ────────────────────────────────────────────
+products:
+  - code: CONSULTING
+    description:
+      en: Consulting Services
+      de: Beratungsleistungen
+      fr: Services de conseil
+      "no": Konsulenttjenester
+    uom: HR
+    price: 100.00
+  - code: TRAINING
+    description:
+      en: Training
+      de: Schulung
+      fr: Formation
+      "no": Opplæring
+    uom: DY
+    price: 800.00
+  - code: REPORT
+    description:
+      en: Written Report
+      de: Schriftlicher Bericht
+      fr: Rapport écrit
+      "no": Skriftlig rapport
+    uom: EA
+    price: 500.00
+  - code: REVIEW
+    description:
+      en: Review & Feedback
+      de: Überprüfung & Feedback
+      fr: Révision et retours
+      "no": Gjennomgang og tilbakemelding
+    uom: HR
+    price: 120.00
+
+# ── Foreign currency options ───────────────────────────────────────────────────
+currencies:
+  - USD
+  - EUR
+  - GBP
+  - JPY
+  - CHF
+  - CAD
+  - AUD
+  - NOK
+  - SEK
+  - DKK
+  - THB
+  - SGD
+  - HKD
+  - INR
+  - MXN
+  - BRL
+  - ZAR
+
+# ── UI label translations ──────────────────────────────────────────────────────
+translations:
+  language:
+    en: Language
+    de: Sprache
+    fr: Langue
+    "no": Språk
+  invoice:
+    en: INVOICE
+    de: RECHNUNG
+    fr: FACTURE
+    "no": FAKTURA
+  sender-name:
+    en: Your Name / Organisation
+    de: Ihr Name / Organisation
+    fr: Votre nom / Organisation
+    "no": Ditt navn / Organisasjon
+  sender-address1:
+    en: Address Line 1
+    de: Adresszeile 1
+    fr: "Ligne d'adresse 1"
+    "no": Adresselinje 1
+  sender-address2:
+    en: Address Line 2
+    de: Adresszeile 2
+    fr: "Ligne d'adresse 2"
+    "no": Adresselinje 2
+  sender-address3:
+    en: Address Line 3
+    de: Adresszeile 3
+    fr: "Ligne d'adresse 3"
+    "no": Adresselinje 3
+  sender-address4:
+    en: Address Line 4
+    de: Adresszeile 4
+    fr: "Ligne d'adresse 4"
+    "no": Adresselinje 4
+  sender-country:
+    en: Country
+    de: Land
+    fr: Pays
+    "no": Land
+  sender-phone:
+    en: Phone
+    de: Telefon
+    fr: Téléphone
+    "no": Telefon
+  sender-email:
+    en: Email
+    de: E-Mail
+    fr: "E-mail"
+    "no": E-post
+  charge-to:
+    en: "Charge to"
+    de: "In Rechnung an"
+    fr: "Facturer à"
+    "no": "Faktureres til"
+  charge-to-name:
+    en: Organisation / Name
+    de: Organisation / Name
+    fr: Organisation / Nom
+    "no": Organisasjon / Navn
+  charge-to-address1:
+    en: Address Line 1
+    de: Adresszeile 1
+    fr: "Ligne d'adresse 1"
+    "no": Adresselinje 1
+  charge-to-address2:
+    en: Address Line 2
+    de: Adresszeile 2
+    fr: "Ligne d'adresse 2"
+    "no": Adresselinje 2
+  charge-to-address3:
+    en: Address Line 3
+    de: Adresszeile 3
+    fr: "Ligne d'adresse 3"
+    "no": Adresselinje 3
+  charge-to-address4:
+    en: Address Line 4
+    de: Adresszeile 4
+    fr: "Ligne d'adresse 4"
+    "no": Adresselinje 4
+  charge-to-country:
+    en: Country
+    de: Land
+    fr: Pays
+    "no": Land
+  charge-to-phone:
+    en: Phone
+    de: Telefon
+    fr: Téléphone
+    "no": Telefon
+  charge-to-email:
+    en: Email
+    de: E-Mail
+    fr: "E-mail"
+    "no": E-post
+  vat-id:
+    en: VAT / Tax ID
+    de: USt-IdNr.
+    fr: "N° TVA / ID fiscal"
+    "no": MVA-nummer
+  invoice-date:
+    en: Invoice date
+    de: Rechnungsdatum
+    fr: Date de facture
+    "no": Fakturadato
+  project-code:
+    en: Project code
+    de: Projektnummer
+    fr: Code projet
+    "no": Prosjektkode
+  invoice-no:
+    en: "Invoice no."
+    de: "Rechnungsnr."
+    fr: "N° de facture"
+    "no": "Fakturanr."
+  qty:
+    en: QTY
+    de: Menge
+    fr: Qté
+    "no": Ant.
+  uom:
+    en: UOM
+    de: Einh.
+    fr: UM
+    "no": Enh.
+  description:
+    en: Description
+    de: Beschreibung
+    fr: Description
+    "no": Beskrivelse
+  price:
+    en: Unit Price
+    de: Einzelpreis
+    fr: Prix unitaire
+    "no": Enhetspris
+  line-total:
+    en: Line Total
+    de: Betrag
+    fr: Total ligne
+    "no": Linjebeløp
+  foreign-currency:
+    en: Foreign currency
+    de: Fremdwährung
+    fr: Devise étrangère
+    "no": Utenlandsk valuta
+  currency-code:
+    en: Currency code
+    de: Währungscode
+    fr: Code devise
+    "no": Valutakode
+  exchange-rate:
+    en: "Exchange rate (1 foreign = X local)"
+    de: "Wechselkurs (1 Fremd = X Inland)"
+    fr: "Taux de change (1 étranger = X local)"
+    "no": "Valutakurs (1 utenlandsk = X lokal)"
+  per-item:
+    en: Price per item (foreign currency)
+    de: Preis je Einheit (Fremdwährung)
+    fr: Prix par unité (devise étrangère)
+    "no": Pris per enhet (utenlandsk valuta)
+  total-local:
+    en: Line total (local currency)
+    de: Zeilenbetrag (Landeswährung)
+    fr: Total ligne (devise locale)
+    "no": Linjebeløp (lokal valuta)
+  add-line:
+    en: "+ Add new line"
+    de: "+ Neue Zeile hinzufügen"
+    fr: "+ Ajouter une ligne"
+    "no": "+ Legg til ny linje"
+  subtotal:
+    en: Subtotal
+    de: Zwischensumme
+    fr: Sous-total
+    "no": Delsum
+  tax:
+    en: Tax
+    de: Steuer
+    fr: Taxe
+    "no": Mva
+  paid:
+    en: Paid
+    de: Bezahlt
+    fr: Payé
+    "no": Betalt
+  to-pay:
+    en: To Pay
+    de: Zu zahlen
+    fr: À payer
+    "no": Å betale
+  generate-invoice:
+    en: Generate Invoice
+    de: Rechnung erstellen
+    fr: Générer la facture
+    "no": Generer faktura
+  other:
+    en: Other
+    de: Andere
+    fr: Autre
+    "no": Annet
+  select:
+    en: "— Select —"
+    de: "— Auswählen —"
+    fr: "— Sélectionner —"
+    "no": "— Velg —"
+  yes:
+    en: "Yes"
+    de: "Ja"
+    fr: "Oui"
+    "no": "Ja"
+  no-option:
+    en: "No"
+    de: "Nein"
+    fr: "Non"
+    "no": "Nei"
+  print-invoice:
+    en: "Print / Save as PDF"
+    de: "Drucken / Als PDF speichern"
+    fr: "Imprimer / Enregistrer en PDF"
+    "no": "Skriv ut / Lagre som PDF"
+  close:
+    en: Close
+    de: Schließen
+    fr: Fermer
+    "no": Lukk
+  invoice-lines:
+    en: Invoice Lines
+    de: Rechnungspositionen
+    fr: Lignes de facture
+    "no": Fakturalinjer
+  sender-section:
+    en: From
+    de: Von
+    fr: De
+    "no": Fra
+  invoice-details-section:
+    en: Invoice Details
+    de: Rechnungsdetails
+    fr: Détails de la facture
+    "no": Fakturaopplysninger