docs(requirements): apply owner corrections; space IDs by 5

- PUBLISH: attempt-level failure wording, no image cap, failure triage rows
- METADATA: title rule is fallback-only (Call 2 not run)
- REVIEW: calculated widths/sqft/bdft not user mutable
- IDs now step by 5 per namespace; rule recorded in STRUCTURE.md

docs/STRUCTURE.md

@@ -60,11 +60,12 @@ Defined only in `docs/REQUIREMENTS.md`, as table rows:
 
 ```
 | ID | Requirement | Scope | Test |
-| CAPTURE-1 | Statement of one testable requirement | shipped | frontend/src/measure/measure.test.ts |
+| CAPTURE-5 | Statement of one testable requirement | shipped | frontend/src/measure/measure.test.ts |
 ```
 
 - `Scope` is `shipped`, `M3`, or `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.
+- IDs advance by 5 within each namespace (`5, 10, 15, ...`), resetting for each prefix. The gaps are intentional room for later insertions; never renumber to close a gap.
 
 ## How to change a requirement