feat(automation): autonomous pipeline with Telegram bot and N8N integration

- Add full auto pipeline: RSS ingest → GPT relevance score → AI rewrite → WP draft
- Add Telegram bot with inline buttons (rewrite/discard/override) and commands (/run, /rejected, /status)
- Add smart publish scheduler: max 2 drafts/day, spread over week (09:00 & 14:00 CET)
- Add N8N API endpoints (/api/n8n/pipeline, /api/n8n/ingest) with X-API-Key auth
- Add GPT-based relevance scoring (0-100) for VanLife/Camping/Outdoor topics
- Remove Ampel risk-level policy check from ingestion (all enabled feeds are used)
- Add Telegram webhook endpoint and setup endpoint
- Add delete_wp_post() for Telegram discard action
- Add DB migrations for relevance_score and scheduled_publish_at columns
- Update .env.example with all new configuration variables
- Add docs/AUTOMATION.md with full setup and usage documentation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/db.py

@@ -160,6 +160,8 @@ def init_db() -> None:
             row["name"] for row in conn.execute("PRAGMA table_info(articles)").fetchall()
         }
         migration_columns = {
+            "relevance_score": "ALTER TABLE articles ADD COLUMN relevance_score INTEGER",
+            "scheduled_publish_at": "ALTER TABLE articles ADD COLUMN scheduled_publish_at TEXT",
             "source_hash": "ALTER TABLE articles ADD COLUMN source_hash TEXT",
             "image_urls_json": "ALTER TABLE articles ADD COLUMN image_urls_json TEXT",
             "press_contact": "ALTER TABLE articles ADD COLUMN press_contact TEXT",