docs(requirements): draft reconciled requirement set (128 rows, 8 namespaces)

Reconciles the scattered requirements onto the owner-job namespaces.

- docs/REQUIREMENTS.md: 128 requirements across CAPTURE, METADATA, REVIEW,
  PUBLISH, SETTINGS, APP, OPS, QUALITY
- docs/STRUCTURE.md: Test may be a path, a requirement ID, or - ;
  a shipped path must exist
- tools/check_requirements.py: resolve test refs accordingly
- .audit/2026-09-18-reconciliation-decisions.md: full decision record plus
  18 deferred rulings for the final cleanup pass

Gate: python tools/check_requirements.py -> PASS

docs/STRUCTURE.md

@@ -64,7 +64,7 @@ Defined only in `docs/REQUIREMENTS.md`, as table rows:
 ```
 
 - `Scope` is `shipped`, `M3`, or `later`.
-- `Test` is a repo-relative path to the test that proves the requirement. Required for `shipped` and `M3`; use `—` for `later`.
+- `Test` is a repo-relative test path, a requirement ID, or `—`. A path given for a `shipped` requirement must exist; a given ID must resolve to a defined requirement.
 
 ## How to change a requirement
 
@@ -80,7 +80,7 @@ Nothing outside `REQUIREMENTS.md` may define a requirement. Capability and contr
 2. Every registered file exists on disk.
 3. Requirement IDs match `^[A-Z]+-\d+$`, are unique, and use a registered prefix.
 4. Scope is one of `shipped | M3 | later`.
-5. `Test` paths for `shipped | M3` requirements exist on disk.
+5. `Test` references resolve: a path given for a `shipped` requirement exists; an ID given resolves to a defined requirement; `—` is allowed.
 6. Requirement rows appear only in `REQUIREMENTS.md`.
 7. Every ID listed in `MILESTONES.md` exists in `REQUIREMENTS.md`.