learn_handler refactored: - Extract LearnParams struct with validation + bounds clamping - Extract store_compacted_memory helper - Extract build_learn_response helper - Reuse check_project_write_access for RBAC ingest_handler refactored: - Extract check_project_write_access (reusable) - Extract execute_ingest helper New tests (6 total): - LearnParams validation tests Total tests: 694 (was 688)