修复 Trellis 空闲态治理检查（07-26-trellis-upgrade-project-audit）

.trellis/spec/hyb-oa/project-governance.md

@@ -101,6 +101,8 @@ rollback and future self-maintenance.
   one deliberately.
 - Post-upgrade dry-run changes manifest again -> investigate template hash drift
   before commit.
+- No active task directory after the last task is archived -> valid idle state;
+  governance still checks core files, docs registration and sensitive content.
 - Only documented project overlays remain modified -> acceptable after task and
   governance gates pass.
 
@@ -118,6 +120,8 @@ rollback and future self-maintenance.
 - Assert CLI and project versions match the intended target.
 - Compile every Python file under `.trellis/scripts` and `.codex/hooks`.
 - Exercise task validate/current/list and run Trellis governance.
+- Archive the final active task and assert Trellis governance still passes with
+  zero active task directories.
 - Confirm no `.new`, backup, bytecode or out-of-scope platform assets are
   tracked; finish with `git diff --check`.