chore: sync .cursor from suite

.cursor/skills/decompose/steps/04_cross-verification.md

@@ -10,6 +10,8 @@
 2. Check no gaps:
    - In implementation mode: every product interface in `architecture.md` has implementation task coverage
    - In tests-only mode: every test scenario in `traceability-matrix.md` is covered by a task
+   - In implementation mode: every named internal runtime capability/dependency from architecture, solution, system flows, and component descriptions has a production implementation task, not only an interface/scaffold/fallback task
+   - In tests-only mode: every e2e/blackbox task has a System Under Test Boundary section that forbids stubbing internal product modules and requires comparison to expected-results artifacts
 3. Check no overlaps: tasks don't duplicate work
 4. Check no circular dependencies in the task graph
 5. Produce `_dependencies_table.md` using `templates/dependencies-table.md`
@@ -19,6 +21,7 @@
 ### Implementation mode
 
 - [ ] Every product interface in `architecture.md` is covered by at least one implementation task
+- [ ] Every named internal runtime capability has a production implementation task
 - [ ] No circular dependencies in the task graph
 - [ ] Cross-component dependencies are explicitly noted in affected task specs
 - [ ] `_dependencies_table.md` contains every task with correct dependencies
@@ -26,6 +29,7 @@
 ### Tests-only mode
 
 - [ ] Every test scenario from `traceability-matrix.md` "Covered" entries has a corresponding task
+- [ ] Every e2e/blackbox task validates actual product behavior and allows stubs only for external systems
 - [ ] No circular dependencies in the task graph
 - [ ] Test task dependencies reference the test infrastructure bootstrap
 - [ ] `_dependencies_table.md` contains every task with correct dependencies