Release v0.8.0

- **Multi-File State Ledger (`[TECH-006]`)**: Introduced decoupled, domain-partitionable feature ledgers (`features.json`) and architectural rejection indexes (`rejections.json`) in `.agents/journal/`.
- **Verifiable Feature Ledger Subcommand (`ajourn feature`)**: Added `ajourn feature <list|add|pass|fail>` supporting domain partitioning (`--domain <name>`), key-by-ID lexicographical sorting, and POSIX lockfile concurrency control.
- **Architectural Rejection Index Subcommand (`ajourn reject`)**: Added `ajourn reject <add|list|lookup>` to record and query discarded proposals with tag normalization and fuzzy text matching.
- **Multi-Ledger Session Ingestion (`ajourn startup`)**: Enhanced `ajourn startup` to automatically display pending/failing features and recent architectural rejections alongside whiteboard state and history.
- **Invocation-Aware Lifecycle Startup Hook**: Added modular `PreInvocation` startup hook (`hooks/pjp-startup.bash`, `hooks/hooks.json`) executing strictly on invocation 1 to ingest workspace ledger state without turn-by-turn notification noise.
- **Specification & Phased Roadmap Alignment**: Authored `docs/technical/specs/multi-file-state-ledger.rst` (`[TECH-006]`) and `docs/project/roadmaps/phase-6-multi-file-state-ledger.rst` (Phase 6).
- **Test Suite Expansion**: Added `Test 14: Verifiable Feature Ledger`, `Test 15: Architectural Rejection Index`, `Test 16: Multi-Ledger Startup Ingestion`, and `Test 17: PJP Lifecycle Startup Hook` to `tests/run_tests.bash`.
- **Noisy Post-Invocation Reminder Hook**: Removed intrusive `hooks/pjp-reminder.bash` and `pjp-reminder` `PostInvocation` configuration from `hooks.json` to prevent turn-by-turn notification pollution and task output contamination.
- **Lifecycle Hook Integration & Message Boundaries**: Streamlined Antigravity hook integration to execute `ajourn startup` strictly on session initialization, preserving clean message envelopes across agent turns and background tasks.