docs: synchronize documentation across all languages

- Add mcp.md to: bg, fa, ru, tr, zh, ar
- Add index.md to Bulgarian (bg)
- Add 24 missing German (de) documentation files

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docs/de/api-http.md

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+# HTTP/REST API
+
+JSON-basierte REST API für Web-Anwendungen.
+
+## Basis-URL
+
+```
+http://localhost:9470/api
+```
+
+## Endpoints
+
+### GET /api/users
+
+Alle Benutzer auflisten:
+
+```bash
+curl http://localhost:9470/api/users
+```
+
+Antwort:
+```json
+[
+  {"id": 1, "name": "Alice", "age": 30},
+  {"id": 2, "name": "Bob", "age": 25}
+]
+```
+
+### GET /api/users/:id
+
+Benutzer nach ID abrufen:
+
+```bash
+curl http://localhost:9470/api/users/1
+```
+
+### POST /api/users
+
+Benutzer erstellen:
+
+```bash
+curl -X POST http://localhost:9470/api/users \
+  -H "Content-Type: application/json" \
+  -d '{"name": "Charlie", "age": 35}'
+```
+
+### PUT /api/users/:id
+
+Benutzer aktualisieren:
+
+```bash
+curl -X PUT http://localhost:9470/api/users/1 \
+  -H "Content-Type: application/json" \
+  -d '{"name": "Alice", "age": 31}'
+```
+
+### DELETE /api/users/:id
+
+Benutzer löschen:
+
+```bash
+curl -X DELETE http://localhost:9470/api/users/1
+```
+
+## Query-Endpoint
+
+BaraQL-Abfragen über HTTP ausführen:
+
+```bash
+curl -X POST http://localhost:9470/api/query \
+  -H "Content-Type: application/json" \
+  -d '{"sql": "SELECT * FROM users WHERE age > 18"}'
+```
+
+## Fehlerantwort
+
+```json
+{
+  "error": {
+    "code": "INVALID_QUERY",
+    "message": "Syntax error at line 1"
+  }
+}
+```
+
+## Authentifizierung
+
+```bash
+curl -H "Authorization: Bearer <token>" \
+  http://localhost:9470/api/users
+```