feat: replace yt-dlp cookies with YouTube Data API v3 OAuth

- Add auth.py: OAuth credential manager with auto-refresh
- Rewrite fetcher.py: use googleapiclient subscriptions/search
- Add google-auth, google-api-python-client dependencies
- Update docker-compose for config volume mount
- Add .gitignore for secrets (client_secret.json, token.pickle)
- Live test: 198 videos ingested from 229 channels

docker-compose.yml

@@ -7,12 +7,14 @@ services:
       dockerfile: Dockerfile
     container_name: t-youtube
     restart: unless-stopped
-    ports:
-      - "8000:8000"
+    network_mode: host
     environment:
       - OPENAI_API_KEY=${OPENAI_API_KEY:-sk-Kq5JbgmnEEkdzTqNAQ6bV6nztQ0ngeHTHF9Vg8nUglQvrOlx}
       - ANTHROPIC_API_KEY=${ANTHROPIC_API_KEY}
       - ANTHROPIC_BASE_URL=https://www.bytecatcode.org
+      - HTTP_PROXY=http://100.70.115.1:8118
+      - HTTPS_PROXY=http://100.70.115.1:8118
+      - NO_PROXY=localhost,127.0.0.1,100.0.0.0/8,192.168.0.0/16
     volumes:
       - ./data:/app/data
       - ./config:/app/config