feat(recovery): stale worktree binding demotion and crash-orphan lease recovery (Closes #702)

An unhandled daemon crash skips teardown: the durable reviewer lease
comment survives, the in-memory session lease dies, and the
auto-reconnected daemon inherits a stale GITEA_ACTIVE_WORKTREE from its
parent environment (PR #701 / branches/review-pr-654 incident).

AC2 — safe clear/re-bind of stale bindings:
- new stale_binding_recovery.py: classifies the active env binding
  (corroborated / unverified_inherited / provably_stale_missing_path /
  superseded_by_session_lease) and produces a fail-closed recovery plan;
  only provably stale bindings are clear-eligible
- gitea_resolve_task_capability and daemon boot run the sanctioned
  recovery (durable audit via session state); runtime context surfaces
  the classification read-only
- namespace_workspace_binding.resolve_namespace_workspace(verify_paths=…)
  demotes env-bound worktrees whose path no longer exists; mutation and
  runtime-context resolution always verify

AC3 — recoverable lease cleanup after unexpected exit:
- durable session-lease shadow (KIND_REVIEWER_SESSION_LEASE) written on
  sanctioned record/heartbeat, removed on sanctioned clear; a crash
  leaves provable orphan evidence (owner pid + session id)
- assess_crashed_session_lease_orphan derives tri-state
  owner_process_alive: only a dead recorded owner pid proves exit; PID
  liveness is never ownership proof
- diagnose/cleanup wrappers consume the shadow instead of passing
  owner_process_alive=None
- new classification orphaned_expired_superseded_head: an expired
  superseded-head lease with no terminal review stops being a permanent
  ambiguous/wait; post-expiry it unlocks fresh acquisition, and guarded
  cleanup becomes eligible only with owner-exit evidence + clean/absent
  worktree + controller authorization + confirmation. Pre-expiry
  behavior is unchanged (fail-closed wait, no steal).

Validation: tests/test_issue_702_stale_binding_lease_recovery.py (29
tests covering lost in-session leases, old-head leases, runtime/worktree
mismatch, managed reconnect, safe expiry); full suite 2665 passed,
6 skipped, 161 subtests.

Co-Authored-By: Claude Fable 5 <[email protected]>

mcp_session_state.py

@@ -36,6 +36,15 @@ KIND_REVIEW_DRAFT = "review_draft"
 # other session proofs; a contaminated session fails closed on gated mutations
 # until a reconciler audits and clears it.
 KIND_STABLE_BRANCH_CONTAMINATION = "stable_branch_contamination"
+# Durable shadow of the in-memory reviewer session lease (#702). Written on
+# every sanctioned record/heartbeat and removed on sanctioned clear, so a
+# daemon that dies without teardown leaves provable orphan evidence (owner
+# pid + session id) for the guarded lease-cleanup path. Never a substitute
+# for the in-session lease: mutation gates ignore it.
+KIND_REVIEWER_SESSION_LEASE = "reviewer_session_lease"
+# Durable audit record written whenever the daemon's sanctioned stale-binding
+# recovery clears an inherited GITEA_ACTIVE_WORKTREE binding (#702).
+KIND_STALE_BINDING_RECOVERY = "stale_binding_recovery"