T7.10 - D5: one analytics implementation, and its report on the admin console

Usage analytics existed as five of the nine colliding globals creator-frame.md
counted (ANALYTICS_KEY, analyticsLoad, analyticsSave, downloadAnalytics,
showAnalytics), twice - and the wizard's copy had no caller, because the
button lived on the creator. The admin console had a THIRD private reader
(usageLoad/downloadUsage) that only saw the wizard's key.

Now: ONE core, html/wp-usage.js (window.WPUsage: load/save/track/download +
the two pre-move storage keys, verbatim). The creator and wizard keep only a
thin track() wrapper - page state like the creator's dev-mode pause belongs
to the page - and record exactly what they recorded before, under the same
keys, so everything captured before this task still reads (probe plants a
legacy-format event and finds it in the report). The "Usage data" button left
the creator toolbar; the report lives in admin.html's usage card, covering
BOTH tools with a download each, behind the same admin gate as the rest of
the console (a non-admin sees the denied card and nothing else), usable at
390px.

Two probes re-pointed, both with the reason in the code:
- cards_check pinned admin.js byte-identical to HEAD - right for T6.5, but as
  a standing probe it would fail every legitimate later edit; D5 targets
  admin.js by name. A7's localization is protected by the feature checks and
  the end-to-end drive, plus a wiring assertion on the block itself.
- frame_check listed "Usage data" among the toolbar buttons that must be
  visible; it now asserts the button is GONE, so the duplicate cannot quietly
  return.

Verification (each probe run alone): NEW tests/usage_check.py 15/15 (grep
half: WPUsage defined once, no page touches the keys directly, none of the
five globals survives anywhere). Regressions: cards_check ALL PASS,
frame_check 39/39.

Items: D5

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

docs/reference/file-map.md

@@ -283,6 +283,7 @@ python tests/triage_check.py         # A6 - the sidebar answers the stand-up
 python tests/qa_gate_check.py        # CR-014/D2/D9/D10 - QA gate + capture sink  40 checks
 python tests/files_check.py          # CR-007/D8 - drawings upload + real offline 36 checks
 python tests/sticky_bar_check.py     # B6 - save reachable on every wizard step   12 checks
+python tests/usage_check.py          # D5 - one analytics core, admin report      15 checks
 ```
 
 **Three probes were re-pointed at `T7.1`.** `sections_check.py` 5b drove the live