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>

tests/run-all.js

@@ -73,9 +73,19 @@ for (const testFile of testFiles) {
 
   console.log(`\n━━━ Running ${displayPath} ━━━`);
 
+  // Run each test hermetically: strip inherited git env vars. When the suite
+  // runs inside a git hook (e.g. pre-push), git sets GIT_DIR/GIT_WORK_TREE,
+  // which would hijack `git -C <dir>` calls in tests that exercise real git
+  // and make them operate on the host repo instead of their own fixtures.
+  const childEnv = { ...process.env };
+  for (const key of ['GIT_DIR', 'GIT_WORK_TREE', 'GIT_INDEX_FILE', 'GIT_COMMON_DIR', 'GIT_PREFIX']) {
+    delete childEnv[key];
+  }
+
   const result = spawnSync('node', [testPath], {
     encoding: 'utf8',
-    stdio: ['pipe', 'pipe', 'pipe']
+    stdio: ['pipe', 'pipe', 'pipe'],
+    env: childEnv
   });
 
   const stdout = result.stdout || '';