feat: phase1 + phase2 - AST ingestion + LangGraph agent + MCP tools

[devam1402]

Phase 1:

• Upgrade docs pipeline with MarkdownHeaderTextSplitter (h1/h2/h3 metadata)
• Add code_ingestion.py: YAML + Python AST parse of kubeflow/manifests
• Rename collection docs_rag to docs_index per gsoc2026_agentic_rag.md
• Docker Compose for local Milvus + etcd + MinIO

Phase 2:

• LangGraph router with docs/code/both routing + routing_logs.jsonl
• MCP tools implementing Thin Context pattern (golden_snippet + URL)
• FastAPI server /chat SSE + /mcp/* endpoints verified 200 OK
• Kagent CRD + KServe manifests for cluster deployment

Ref: gsoc2026_agentic_rag.md" POC

[google-oss-prow]

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