fix: per-page WASM render mode, Contact checkbox binding, Telegram inquiry channel

- Admin: replace the global @rendermode on <Routes>/<Router> with per-page
  render mode. Login.razor now prerenders (form visible before WASM loads);
  every other [Authorize] page stays prerender: false to avoid the
  AuthorizeRouteView blank-render regression from earlier attempts. Adds a
  "준비 중" -> "로그인" splash tied to WASM boot completion, and lets the
  authenticated-shell loading overlay stay up until AdminShell actually renders.
- Contact.cshtml: fix the "Agree" checkbox missing value="true" - a checked
  box sent the browser-default "on", which bool model binding can't parse,
  so ModelState.IsValid silently went false and OnPostAsync returned a blank
  form with no visible error on every submission. Validation summary widened
  from ModelOnly to All so this class of failure isn't silent again.
- TelegramInquiryNotificationService: read Telegram:InquiryChatId (falling
  back to ChatId) instead of only ChatId, matching the channel routing
  CLAUDE.md documents and deploy.yml already provisions as separate secrets.
- Reconcile CLAUDE.md's self-contradicting Phase 8 prerender notes (Phase 9),
  rewrite validate_admin_render.sh for the per-page design, and add a
  SmartAdmin 5.5 design reference section to DOUZONE_UX_GUIDE.md for future
  admin screens (existing screens unchanged, tracked as WBS P4-03).

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

docs/ADMIN_PATTERN_CRITIQUE_WBS.md

@@ -78,6 +78,7 @@ Razor Page/Form
 | P5-01 | CI gate 명문화 | workflow 체크 목록 | 6개 gate 모두 required |
 | P5-02 | 배포본 API smoke 확장 | workflow curl 추가 | Blog/Inquiry create-read-update test 2xx |
 | P5-03 | 운영 회귀 대시보드 | test report/version endpoint | 배포 커밋과 E2E 결과 추적 가능 |
+| P4-03 | 기존 20개+ 어드민 화면을 SmartAdmin 5.5 참조(`legacy/smartadmin/`, `DOUZONE_UX_GUIDE.md`)로 재단장 (2026-07-03 시점 미착수, 향후 별도 진행) | 각 화면의 색상/카드/타이포그래피 갱신 | SmartAdmin 매핑 표 기준 적용 화면 수 / 전체 화면 수 100% |
 
 ## Immediate Refactor Order