docs(review): correct R8/R13 and the plan status; bump user pin to the review fixes

R8 and R13 both described behaviour that changed in review, and R13 rested on a
server-side cleanCoordinate() that had never been committed. Both now describe
what actually ships, with the revision called out inline rather than silently
rewritten. The plan's Status keeps ✅ Complete but now records what the review
changed and the two things still open before merge.

Bumps the `user` gitlink to e873a9c (the review fixes). The submodule is
deliberately NOT pushed: git-sync would propagate it to production. So this pin
still references a commit that exists only locally — push `user/` and re-point
before this branch merges.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/working/specs/2026-07-23-post-form-location-override-design.md

@@ -64,8 +64,8 @@ Backend sanitization has already been added (`user/plugins/cache-on-save/cache-o
 ### Error handling
 
 - No search results: inline message under the search box, map/pin untouched.
-- Search network failure: silent-ish degrade (consistent with existing weather/reverse-geocode error handling in `post-form.js`), fields untouched.
-- Invalid manual `lat`/`lng` text: no client-side hard block (the map preview and eventual server-side `cleanCoordinate()` are the safety nets); this UI's whole point is to make that failure mode rare in practice, not to duplicate the backend validator client-side.
+- Search network failure: fields untouched, and an inline hint says the lookup service could not be reached (distinct from the no-results message, which means the service answered). **Revised in code review 2026-07-24** — this originally said "silent-ish degrade", which in practice left the DOM byte-identical to the pre-click state, so a traveller on flaky mobile data could not tell a failed lookup from a broken button. A non-2xx response is also now treated as a failure rather than parsed as an empty result set.
+- Invalid manual `lat`/`lng` text: the visual mismatch flag is the primary feedback, **and** an unresolved flag blocks submit. **Revised in code review 2026-07-24** — this originally said "no client-side hard block", on the stated grounds that server-side `cleanCoordinate()` was already the safety net. It was not: `cleanCoordinate()` had never been committed, so nothing validated coordinates anywhere. It now ships (`cache-on-save.php`, both the `/post` and Admin2 paths), so the two are genuine defence in depth rather than one imaginary net. Client-side parsing is deliberately *stricter* than the server's `is_numeric` (whole-value decimals only), which is the safe direction for a mismatch.
 - Geolocation permission denied: unchanged existing behavior (`#location-status` error message).
 
 ## Out of scope / explicitly deferred