Deploy the Bublik AI assistant

[okt-limonikas]

Summary

Update the Docker deployment for streaming AI chat, provider credentials, file
rendering, and S3-compatible generated-file storage. Bundle a loopback-only
SeaweedFS service and include the corresponding administrator documentation.

Related

• Add the configurable Bublik AI assistant backend bublik#348
• Add the Bublik AI assistant interface bublik-ui#606
• docs(ai): document chat configuration and deployment bublik-release#58

Changes

• Run Django with Gunicorn and uvicorn_worker.UvicornWorker against the ASGI app.
• Run the development server with Uvicorn.
• Disable Nginx buffering and caching for /api/v2/chat.
• Load .env for services that need AI provider credentials.
• Install native libraries and fonts needed for document/PDF generation.
• Add Redis URL, public Bublik URL, ASGI, S3, and file-size settings.
• Add chrislusf/seaweedfs:4.40 with loopback binding and persistent storage.
• Document provider configuration, architecture, storage, deployment, backup,
  verification, security, and troubleshooting.
• Update backend, frontend, and release-documentation revisions.

New Settings

Variable	Default
S3_ENDPOINT_URL	http://127.0.0.1:8333
S3_PUBLIC_ENDPOINT_URL	empty
S3_ACCESS_KEY	bublik
S3_SECRET_KEY	bublik-secret-key
S3_BUCKET	bublik-chat-files
S3_REGION	us-east-1
S3_PRESIGN_EXPIRY	300
CHAT_FILE_MAX_SIZE	20971520
BUBLIK_DOCKER_SEAWEEDFS_S3_PORT	8333

Provider credentials use deployment-specific uppercase AI_* variables, for
example AI_OPENAI_API_KEY and AI_ANTHROPIC_API_KEY.

Upgrade Notes

• Back up PostgreSQL and generated-file storage before updating.
• The normal database backup does not include the seaweedfs_data named volume.
• Change the bundled object-storage credentials if its endpoint is exposed.
• Restricted-network deployments must transfer the SeaweedFS image.
• The Django entrypoint applies the new chat migrations automatically.