feat(embed,ui04): E07 acceptance — matrix completion, hostile-CSS hardening, measurements and record closure

- E07 e2e (7 cases): 4-viewport fixed size, narrow shrink + dual-slot 12px stack, single/static + empty state + two-photo loop copies, broken-thumb drop, reducedMotion stop with manual arrows, forged postMessage rejected, hostile CSS (!important box-sizing/border) with inline-important countermeasures + duplicate script dedup
- loader v2: geometry-critical properties upgraded to inline !important (beats host stylesheet !important)
- pre-existing fixes: likes.spec view-count assertion vs concurrent session's AlbumHeader unicode icons (toContainText); embed-v2 host port moved to 3998 (3999 collides with embed-crossorigin under parallel full runs); prettier formatting of two concurrent-session files (formatting-only)
- evidence: matrix EMB-A01..A16 closed in acceptance record (mechanism-level items honestly marked), measurements (loader v2 9885B/gzip 3959B, first-load 1 GET + 1 WS, DOM<=16), refreshed screenshots/recordings, master plan UI-04 note
- regression: root lint/typecheck/test 12 packages green; embed suites 43/43; admin embed-slots 5/5; journey pre-existing env failure reproduced at clean HEAD (registered)

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

apps/admin/src/utils/system/embedSlots.spec.ts

@@ -320,7 +320,7 @@ describe('buildPreviewPlacement 本地预览停靠几何（草稿即时反映，
   })
 
   it('mobile：窄屏强制 sm + 默认收起（§5.4 <480px）；宽度按剩余宽收缩防溢出（carousel）', () => {
-    const v1 = { ...DEFAULT_EMBED_SETTINGS, displayMode: 'carousel' }
+    const v1: EmbedSettingsDraft = { ...DEFAULT_EMBED_SETTINGS, displayMode: 'carousel' }
     const placement = buildPreviewPlacement(v1, 'mobile')
     expect(placement.size).toBe('sm')
     expect(placement.width).toBe(280)