test(ui): five verification rounds, and two things they found

Five rounds, each looking from an angle the previous one cannot:

  1. text     — every "Thay đổi" bullet on the page vs a probe (existing)
  2. geometry — check_layout_geometry.py: reading order of the rail, section
                order down Monitoring, which side each pane is on, and the size
                relationships the design names (hero card, 26px dot)
  3. inventory— check_controls_alive.py: every control in controls.json still
                present in the built app, attributed to its owning CLASS via the
                baseline commit (a file holds several classes, so a per-file
                check reported eight dialog controls as missing)
  4. eyes     — rendered screens read against the wireframes
  5. adversarial — check_probes_bite.py: break one feature at a time and fail if
                the matching check still passes

What rounds 4 and 5 caught, which 1-3 could not:

  * Schedule showed six of seven lanes; the seventh needed a horizontal
    scroll. The design says "giữ đủ 7 lane, thu hẹp cho vừa một màn". Lane
    minimum width 190 → 150, so 7 × 150 + gaps fits a 1280 window. Round 2 now
    measures this instead of relying on someone noticing.

  * check_design_parity ALWAYS returned 0. It was a report, not a check: every
    probe in it was incapable of failing, so a regression would print on screen
    and still exit green. It now exits non-zero when anything is CHUA — which
    is what let round 5 detect the two mutations it had been sleeping through.

Also fixed in the harness itself: it rewrote line endings while restoring
mutated files (read_text/write_text translate both ways), and it compared the
tree against "clean" rather than against its own starting state.

All ten checkers green by exit code.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tools/check_design_parity.py

@@ -346,7 +346,10 @@ def main() -> int:
     print(f"  OK   = dung thiet ke moi ({counts['OK']}/{len(R)})")
     print(f"  KHAC = co y lam khac, da ghi ly do")
     print(f"  CHUA = chua lam")
-    return 0
+    # This used to return 0 unconditionally — a report, not a check. Every probe
+    # in it was therefore unable to fail, so a regression would have been shown
+    # on screen and still exited green for any script that only reads the code.
+    return 1 if counts.get("CHUA") else 0
 
 
 if __name__ == "__main__":