docs: mark P2 backlog items complete in ROADMAP

Updated ROADMAP to reflect shipped P2 items:
- P2.7: Canonical lane event schema in clawhip
- P2.8: Failure taxonomy + blocker normalization
- P2.9: Stale-branch detection before workspace tests
- P2.10: MCP structured degraded-startup reporting
- P2.12: Lane board / machine-readable status API

Remaining P2: P2.11 (task packets - in progress), P2.14 (config merge), P2.15 (flaky test)

ROADMAP.md

@@ -281,12 +281,12 @@ Priority order: P0 = blocks CI/green state, P1 = blocks integration wiring, P2 =
 **P2 — Clawability hardening (original backlog)**
 5. Worker readiness handshake + trust resolution — **done**: `WorkerStatus` state machine with `Spawning` → `TrustRequired` → `ReadyForPrompt` → `PromptAccepted` → `Running` lifecycle, `trust_auto_resolve` + `trust_gate_cleared` gating
 6. Prompt misdelivery detection and recovery — **done**: `prompt_delivery_attempts` counter, `PromptMisdelivery` event detection, `auto_recover_prompt_misdelivery` + `replay_prompt` recovery arm
-7. Canonical lane event schema in clawhip
-8. Failure taxonomy + blocker normalization
-9. Stale-branch detection before workspace tests
-10. MCP structured degraded-startup reporting
+7. Canonical lane event schema in clawhip — **done**: `LaneEvent` enum with `Started/Blocked/Failed/Finished` variants, `LaneEvent::new()` typed constructor, `tools/src/lib.rs` integration
+8. Failure taxonomy + blocker normalization — **done**: `WorkerFailureKind` enum (`TrustGate/PromptDelivery/Protocol/Provider`), `FailureScenario::from_worker_failure_kind()` bridge to recovery recipes
+9. Stale-branch detection before workspace tests — **done**: `stale_branch.rs` module with freshness detection, behind/ahead metrics, policy integration
+10. MCP structured degraded-startup reporting — **done**: `McpManager` degraded-startup reporting (+183 lines in `mcp_stdio.rs`), failed server classification (startup/handshake/config/partial), structured `failed_servers` + `recovery_recommendations` in tool output
 11. Structured task packet format
-12. Lane board / machine-readable status API
+12. Lane board / machine-readable status API — **done**: Lane completion hardening + `LaneContext::completed` auto-detection + MCP degraded reporting surface machine-readable state
 13. **Session completion failure classification** — **done**: `WorkerFailureKind::Provider` + `observe_completion()` + recovery recipe bridge landed
 14. **Config merge validation gap** — merged settings (especially `hooks`) can produce non-string array values that fail validation at `claw --help` time; error path: `deep_merge_objects()` → malformed hooks → `optional_string_array()` parse error
 15. **MCP manager discovery flaky test** — `manager_discovery_report_keeps_healthy_servers_when_one_server_fails` has intermittent timing issues in CI; temporarily ignored, needs root cause fix