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/test/shim-better-sqlite3.mjs

@@ -0,0 +1,24 @@
+// Test-only shim: maps the better-sqlite3 API onto Node's built-in node:sqlite.
+// Used ONLY for local integration testing (production uses real better-sqlite3
+// inside the Docker image). The SQL executed is identical.
+import { DatabaseSync } from 'node:sqlite';
+
+class Statement {
+  constructor(stmt) {
+    this.stmt = stmt;
+    if (typeof stmt.setAllowBareNamedParameters === 'function') {
+      stmt.setAllowBareNamedParameters(true);
+    }
+  }
+  run(...args) { return this.stmt.run(...args); }
+  get(...args) { return this.stmt.get(...args); }
+  all(...args) { return this.stmt.all(...args); }
+}
+
+export default class Database {
+  constructor(path) { this.db = new DatabaseSync(path); }
+  pragma(s) { return this.db.exec('PRAGMA ' + s + ';'); }
+  exec(sql) { return this.db.exec(sql); }
+  prepare(sql) { return new Statement(this.db.prepare(sql)); }
+  close() { this.db.close(); }
+}