Fix missing icon broken image, clean up debug logs, expand test cases

- iconEl: use actual icon filename as <img src> fallback so browser
  shows a visible broken image when the file is missing (was src="")
- Remove debug console.log statements added for diagnosis
- home.md: add test cases for message: override (with console warning)
  and missing icon (broken image should render)
- home.md: add explanatory text for message: key test

https://claude.ai/code/session_01UP8Wo2CKPNhvvTkzX48CWF

app/index.html

@@ -956,7 +956,8 @@ body {
     const svg = getIcon(name);
     const span = document.createElement('span');
     span.className = 'mdcms-icon' + (className ? ' ' + className : '');
-    span.innerHTML = svg || '<img src="" alt="" style="width:1em;height:1em;">';
+    const filename = normaliseIconName(name);
+    span.innerHTML = svg || '<img src="assets/icons/' + filename + '" alt="[missing: ' + filename + ']" style="width:1em;height:1em;display:inline-block;">';
     return span;
   }
 
@@ -1815,7 +1816,6 @@ function fmtDatetime(dtStr) {
   };
 
   function renderCalloutTag(container, tag) {
-    console.log('[mdcms callout] tag:', tag.tagName, '| options:', JSON.stringify(tag.options), '| body:', (tag.body || '').slice(0, 60));
     var typeMatch = tag.tagName.match(/^callout-(info|warning|success|error)$/);
     var calloutType = typeMatch ? typeMatch[1] : 'info';
 
@@ -1824,7 +1824,6 @@ function fmtDatetime(dtStr) {
     var title = opts.title || null;
     var iconName = opts.icon || null;
     var bodyMd = tag.body || '';
-    console.log('[mdcms callout] title =', JSON.stringify(title), '| msgKey =', msgKey);
 
     // Resolve message: key — config.yml callouts block
     if (msgKey) {
@@ -1863,17 +1862,14 @@ function fmtDatetime(dtStr) {
     container.style.setProperty('--callout-bg', hexToRgba(bgColour, 0.08));
 
     if (title) {
-      console.log('[mdcms callout] creating title row:', title);
       var titleRow = document.createElement('div');
       titleRow.className = 'mdcms-callout-title';
-      titleRow.style.color = primaryColour;  // bypass CSS var cascade
+      titleRow.style.color = primaryColour;
       titleRow.appendChild(iconEl(iconName));
       var titleText = document.createElement('span');
       titleText.textContent = title;
       titleRow.appendChild(titleText);
       container.appendChild(titleRow);
-    } else {
-      console.log('[mdcms callout] no title — skipping title row');
     }
 
     if (bodyMd) {

app/pages/home.md

@@ -68,10 +68,36 @@ This info callout uses the warning icon instead of the default info icon.
 
 ## Config-defined message (message: key)
 
-```mdcms callout-warning
+The callout below uses `message: aitranslation` to pull its title and body from the `callouts:` block in `config.yml`. The type (`warning`) also comes from the config entry, not the tag name.
+
+```mdcms callout-info
 message: aitranslation
 ```
 
 ---
 
+## message: overrides inline content
+
+When `message:` is present, any inline `title:` or body text is ignored. A warning should appear in the browser console.
+
+```mdcms callout-info
+message: aitranslation
+title: This title should be ignored
+This body text should also be ignored. Check the console for a warning.
+```
+
+---
+
+## Missing icon
+
+This callout uses a non-existent icon name. A broken image should appear where the icon would be.
+
+```mdcms callout-info
+title: Custom icon that does not exist
+icon: nonexistent_icon
+The icon to the left of this title should show as a broken image.
+```
+
+---
+
 Toggle dark mode and check all four callout types still look correct.