Add run.sh to handle venv setup automatically

Creates .venv on first run, installs dependencies, then starts the server.
Subsequent runs skip straight to starting. Avoids externally-managed-environment
errors on Debian/Ubuntu 12+.

https://claude.ai/code/session_01JuRTR5Xjx8emQsyerBgGU7

run.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+# Run ClubLedger – creates a virtualenv on first run, then starts the server.
+set -e
+
+VENV=".venv"
+
+if [ ! -d "$VENV" ]; then
+    echo "Creating virtual environment..."
+    python3 -m venv "$VENV"
+    echo "Installing dependencies..."
+    "$VENV/bin/pip" install --quiet -r requirements.txt
+    echo "Done."
+fi
+
+exec "$VENV/bin/python" main.py "$@"