#2 feat: transparent leader hint reconnect on consume

Summary

• When consume receives gRPC UNAVAILABLE with x-fila-leader-addr trailing metadata, the client transparently reconnects to the leader address and retries once
• Applies to both sync Client and async AsyncClient
• Connection parameters (TLS certs, API key) are stored and reused when creating the redirected channel
• Max 1 redirect per consume call to prevent infinite loops

Test plan

• Verify existing integration tests still pass (no behavior change for non-cluster setups)
• Test with a multi-node cluster where consumer connects to a follower node
• Verify UNAVAILABLE without leader hint metadata still raises RPCError
• Verify second UNAVAILABLE after redirect raises RPCError (no infinite loop)

🤖 Generated with Claude Code

---

Summary by cubic

Automatically reconnects to the hinted leader and retry once when a consume call hits a follower. Works for both sync Client and AsyncClient, reuses TLS/mTLS credentials and API key, and closes the old channel before reconnecting.

• New Features

  • Detects gRPC UNAVAILABLE with x-fila-leader-addr and retries consume against the leader once.
  • Reuses stored TLS CA and optional client cert/key plus API key when creating the new channel.
  • If no leader hint is present, or the retry fails, the client raises the mapped RPCError.

• Bug Fixes

  • Closes the previous gRPC channel before reconnecting to avoid leaked connections.
  • Resolves mypy no-any-return issues by adding return types and channel factory helpers (no behavior change).