chore: monorepo - plugin, backend und hilfsdaten in einem repo

- Eltern-Ordner ist jetzt EIN Git-Repo (statt getrennter Repos).
- root .gitignore haelt Secrets (.env), node_modules, DB und Build-Artefakte raus.
- release.ps1: manueller Release (ZIP bauen + ans Backend laden).
- root README mit Struktur und Release-Ablauf.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

license-backend/Dockerfile

@@ -0,0 +1,24 @@
+# Node 20 on glibc so better-sqlite3 uses prebuilt binaries (no native build).
+FROM node:20-bookworm-slim
+
+ENV NODE_ENV=production
+WORKDIR /app
+
+# Install dependencies first for better layer caching.
+COPY package.json ./
+RUN npm install --omit=dev --no-audit --no-fund
+
+# App source.
+COPY src ./src
+
+# Persistent data directory (mounted as a volume in compose).
+RUN mkdir -p /data && chown -R node:node /data /app
+VOLUME ["/data"]
+
+USER node
+EXPOSE 8080
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+  CMD node -e "fetch('http://127.0.0.1:'+(process.env.PORT||8080)+'/healthz').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))"
+
+CMD ["node", "src/server.js"]