cbc3b075a0
Track + metadata + state + tracks.md registration for the Fleury-pattern error handling refactor. Key design decisions (per user approval): - Option A for _send_<vendor>() handling: rename to _send_<vendor>_result() and change return type to Result[str] (contained to internal callers). - send() is marked @typing_extensions.deprecated; send_result() is the new public API. - ProviderError exception is FULLY REPLACED by ErrorInfo dataclass (a value, not an exception). - 5 phases: foundation, mcp_client, ai_client, rag_engine, deprecation+archive. - Post-tracks baseline check (Phase 1 Task 1.1) verifies the 3 pending tracks have merged before proceeding. - 9 Open Questions, 7 Risks, 5 verification criteria, follow-up track public_api_migration_20260606 planned in spec §12.1. Blocked by: startup_speedup_20260606, test_batching_refactor_20260606, qwen_llama_grok_integration_20260606. Blocks: public_api_migration_20260606.