Add full project structure: backend, frontend, Docker, and CI workflows

- Organize backend into src/ (routes/, services/, db/) per package.json entrypoint
- Add migrations/import-mdb.js for one-time .mdb → SQLite migration
- Add public/ frontend: check ledger table, slide-in new/edit panel, PDF generation
- Add docker/Dockerfile and docker-compose.yml for self-hosted deployment
- Add .github/workflows: Docker Hub build+push on main/tags, TODO→Issues scanner
- Add GnuMICR font files (GPL-2.0) for MICR E-13B line rendering

docker/Dockerfile

@@ -0,0 +1,18 @@
+FROM node:20-alpine
+
+# mdbtools for migration script (only needed on first run, stays in image for convenience)
+RUN apk add --no-cache mdbtools
+
+WORKDIR /app
+
+COPY package*.json ./
+RUN npm ci --omit=dev
+
+COPY . .
+
+# Data volume: SQLite database and any runtime uploads
+VOLUME ["/app/data"]
+
+EXPOSE 3000
+
+CMD ["node", "src/app.js"]