feat: worktree-lifecycle service (deterministic conflict prediction + safe GC) (#2164)

* feat: add worktree-lifecycle service (ecc.worktree-lifecycle.v1)

The "unowned moat" from the orchestrator landscape research: no existing
tool ships deterministic merge-conflict prediction or a safe worktree GC.

- scripts/lib/worktree-lifecycle/git.js: injectable, hermetic git layer.
  Predicts merge conflicts WITHOUT touching the working tree via
  `git merge-tree`. Strips inherited GIT_* env so it is safe inside hooks.
- scripts/lib/worktree-lifecycle/lifecycle.js: deterministic state machine
  (main/dirty/conflict/merge-ready/merged/stale/idle) + planCleanup that
  buckets worktrees into remove / salvage / keep. Only fully-merged trees
  are auto-removable; stale (unmerged+inactive) => salvage, never deleted.
- scripts/worktree-lifecycle.js: CLI (--json/--conflicts/--stale/
  --cleanup-plan/--base/--stale-days/--repo).
- tests/lib/worktree-lifecycle.test.js: 11 tests (fake-git + real-git).

Safety model mirrors the reference-arch salvage rule, validated by the
2026-06-05 MacBook->Mac Mini consolidation. Tests: 11/0.

* fix: hermetic git env in session adapters + mcp-inventory lint

- session adapters (codex-worktree, opencode): resolveGitBranch stripped
  no git env, so the "outside a repo" path returned the host branch when
  run inside a git hook (GIT_DIR set). Strip GIT_* before rev-parse.
- mcp-inventory: fix eslint no-unused-vars (signatures) and a stale
  eslint-disable directive in the merged code.

* test: run each test with inherited git env stripped (hermetic runner)

When the suite runs inside a git hook (pre-push), git sets GIT_DIR/
GIT_WORK_TREE, which hijack 'git -C <dir>' calls in tests that exercise
real git, making them operate on the host repo. Strip GIT_* before
spawning each test so the suite is isolated from ambient git state.

---------

Co-authored-by: ECC Test <ecc@example.test>

scripts/lib/mcp-inventory/canonical-mcp.js

@@ -219,7 +219,7 @@ function mergeServers(serverRecords) {
 
   return Array.from(byName.values()).map(server => {
     const uniqueSignatures = Array.from(new Set(server.signatures));
-    const { signatures, ...rest } = server;
+    const { signatures: _signatures, ...rest } = server;
     return {
       ...rest,
       harnessCount: server.sources.length,

scripts/lib/mcp-inventory/readers/codex.js

@@ -19,7 +19,6 @@ function loadTomlParser(parseTomlImpl) {
   }
 
   try {
-    // eslint-disable-next-line global-require
     return require('@iarna/toml').parse;
   } catch {
     return null;