chore: WIP pre-implement

Bundled hygiene commit before cycle-3 /implement (AZ-776, AZ-777). Mixes
two concerns by user choice (autodev option B):

- Cycle-3 autodev artifacts not yet committed by Step 9 (new-task):
  task specs for AZ-776 / AZ-777 under _docs/02_tasks/todo/ and the
  updated _docs/02_tasks/_dependencies_table.md.
- Accumulated skill / rule tooling maintenance under .cursor/ (skills:
  autodev, code-review, decompose, deploy, implement, new-task, plan,
  refactor, retrospective, test-spec; rules: coderule, cursor-meta,
  meta-rule, testing; new release skill scaffolding).
- Autodev bootstrap state: _docs/_autodev_state.md (step 10 in_progress)
  and _docs/_process_leftovers/2026-05-11_d_cross_cve_1_opencv_pin_deferred.md
  (replay timestamp refreshed; gtsam 4.2 still numpy<2-only).

Co-authored-by: Cursor <cursoragent@cursor.com>

.cursor/skills/test-spec/phases/03-data-validation-gate.md

@@ -1,7 +1,7 @@
 # Phase 3: Test Data & Expected Results Validation Gate (HARD GATE)
 
 **Role**: Professional Quality Assurance Engineer
-**Goal**: Ensure every test scenario produced in Phase 2 has concrete, sufficient test data. Remove tests that lack data. Verify final coverage stays above 75%.
+**Goal**: Ensure every test scenario produced in Phase 2 has concrete, sufficient test data. Remove tests that lack data. Verify final coverage stays above the canonical threshold (currently 75% — see `.cursor/rules/cursor-meta.mdc` Quality Thresholds; never hardcode a different number in any phase).
 **Constraints**: This phase is MANDATORY and cannot be skipped.
 
 ## Step 1 — Build the requirements checklist