fix(post): cover the code-review fixes; mark location-override plan complete

Adds Playwright coverage for the four cross-reviewer-confirmed bugs
fixed in the user/ submodule (map-load race on rapid reopen, mismatch
flag clearing on blank, and submit blocked on unresolved mismatch),
and bumps the user/ pointer to the commit with those fixes.

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

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

@@ -11,7 +11,7 @@ execution: code
 
 # Post Form Location Override - Plan
 
-**Status:** 📋 Not started
+**Status:** ✅ Complete (2026-07-24)
 
 ## Goal Capsule