fix: address 8 code review issues for Rustagent V2 Phase 1 master
CRITICAL: - C1: Fix create_session call in run command (was passing wrong arguments) IMPORTANT: - I1: Add blocked_reason parameter to update_node trait and implementations - I2: Add unit test for ContextBuilder::build_system_prompt output format - I3: Fix clippy type_complexity warning in MockLlmClient with type alias - I4: Prefix unused variable with underscore in interchange_test.rs - I5: Add #![allow(dead_code)] to tests/common/mod.rs MINOR: - M1: Remove unnecessary #[allow(dead_code)] from resolve_project in main.rs - M2: Wrap create_session INSERT in BEGIN IMMEDIATE transaction All tests pass (173 passed), clippy clean, code formatted. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>