fix: robust OCR/image ingestion parsing and add one-click Supabase document deletion to Search Playground

fix: auto-select active document on load and ingestion finish so search is never disabled

fix: align all UI model documentation strings with Tencent Hy3 + Gemini 3.1 Flash backend

fix: update UI labels to accurately reflect Gemini 3.1 Flash as the active RAGAS judge

Update RAG application backend, LLM services, ingest file safety and frontend components

Elaborate RAG Fundamentals page with real-world applications and concrete examples

feat: enterprise multi-page RAG platform with GraphRAG, CRAG, Guardrails, and VectorDB Inspector