feat: replace blinko with affine, route notifications to telegram

- Add AFFiNE stack (affine.pivoine.art): main app, migration job,
  redis, pgvector postgres
- Remove blinko stack
- Update backup.sh: swap blinko_db → affine_db
- Update README

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

README.md

@@ -13,7 +13,7 @@ Each stack is independently deployable with its own `compose.yml` and `.env`. Al
 | `watchtower` | Automatic container updates | watchtower |
 | `umami` | Web analytics | umami, db |
 | `immich` | Photo & video management | immich, ml, redis, db |
-| `blinko` | AI-powered personal notes | blinko, db |
+| `affine` | Collaborative workspace & notes | affine, redis, db |
 | `n8n` | Workflow automation & notification relay | n8n, db |
 | `gitea` | Git hosting + CI runner | gitea, runner, db |
 | `coolify` | Deployment platform | coolify, realtime, redis, db |