Fix Docker volume permissions for SQLite database

Container runs as non-root user but mounted volumes may be owned by root.
Added entrypoint script to fix /data permissions before starting the app.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

entrypoint.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+set -e
+
+# Ensure /data directory exists and is writable
+# This handles the case where a Docker volume is mounted with root ownership
+if [ ! -w /data ]; then
+    echo "Warning: /data not writable, attempting to fix permissions..."
+    # This will only work if running as root
+    chown -R mcp:mcp /data 2>/dev/null || true
+fi
+
+# Create the data directory if it doesn't exist
+mkdir -p /data 2>/dev/null || true
+
+exec "$@"