sloproxy

refactor(session): prune in-memory session tree store in favor of flat KV affinity and pure info extraction master

- Replace complex materialized tree structures with lightweight (session_id, parent_id) extraction - Maintain O(1) flat KV cache for subagent-to-parent prompt cache inheritance - Add tree_compat.go with deprecated stubs to preserve SDK compatibility - Add comprehensive regression tests for multi-protocol session headers and payloads