Enhance knowledge base functionality and integrate S3 storage support

- Add new models for `KnowledgeDocument` and `KnowledgeChunk` to manage document ingestion and chunking.
- Implement S3-compatible storage integration for knowledge documents, allowing for file uploads and retrieval.
- Introduce API endpoints for managing knowledge bases and documents, including creation, deletion, and searching.
- Update frontend components to support knowledge base configuration and document management, improving user interaction.
- Enhance backend services for knowledge processing and retrieval, ensuring robust handling of document statuses and errors.

backend/settings.py

@@ -46,3 +46,12 @@ TURN_SECRET = os.getenv("TURN_SECRET", "")
 TURN_USERNAME = os.getenv("TURN_USERNAME", "")
 TURN_PASSWORD = os.getenv("TURN_PASSWORD", "")
 TURN_CREDENTIAL_TTL = int(os.getenv("TURN_CREDENTIAL_TTL", "86400"))
+
+# ---- S3-compatible object storage (RustFS in local compose) ----
+S3_ENDPOINT_URL = os.getenv("S3_ENDPOINT_URL", "http://localhost:9000")
+S3_ACCESS_KEY = os.getenv("S3_ACCESS_KEY", "rustfsadmin")
+S3_SECRET_KEY = os.getenv("S3_SECRET_KEY", "rustfsadmin")
+S3_BUCKET = os.getenv("S3_BUCKET", "ai-video")
+S3_REGION = os.getenv("S3_REGION", "us-east-1")
+KNOWLEDGE_MAX_FILE_BYTES = int(os.getenv("KNOWLEDGE_MAX_FILE_BYTES", "20971520"))
+KNOWLEDGE_TOP_K = int(os.getenv("KNOWLEDGE_TOP_K", "5"))