fix(full-page): preserve large page rects and force image/graphics redaction

[theodubus]

Motivation

• Some PDFs showed visible headers/logos after a full-page redaction because large page rectangles were being vertically tightened or non-text elements (images/vector graphics) were not removed. This produced rare but important visual leaks.
• Add a regression test to ensure a full-page rectangle actually removes the target content in the exported PDF.

Description

• Backend: avoid aggressive vertical tightening for large rectangles by skipping _tighten_rect_vertical when rectangle height exceeds 24.0 pt to preserve full-page rect coverage (backend/app/redaction.py).
• Backend tests: add an integration test test_redact_rectangles_full_page_rect_redacts_target that posts a full-page rectangle to /redact/rectangles and asserts the secret is removed (backend/tests/test_redact_rectangles.py).
• Frontend: include page rules' rects in the API payload and detect when at least one full-page rule exists (frontend/src/App.tsx and frontend/src/types/uiRules.ts).
• Frontend API: send explicit options.apply_images and options.apply_graphics to /redact/apply when full-page rules are present so images and vector graphics are also redacted (frontend/src/api.ts).
• Frontend UI: track current visible page via an IntersectionObserver in PdfViewer, expose onCurrentPageChange, render the page censor preview, and wire a "censor page" action to create page rules (frontend/src/components/PdfViewer.tsx, frontend/src/components/Rules/RulesSection.tsx, frontend/src/components/Rules/RulesList.tsx, frontend/src/components/Rules/EditRuleModal.tsx).
• Localization: add rules.badge.page and rules.page.title translations for EN/FR (frontend/src/locales/en.json, frontend/src/locales/fr.json).

Testing

• Frontend production build: ran npm run build in frontend/ and it completed successfully. ✅
• Frontend dev + UI check: started the dev server and captured a browser screenshot with Playwright to validate the UI wiring and the page-redaction controls. ✅
• Backend integration test: added test_redact_rectangles_full_page_rect_redacts_target to prevent regressions, but the new backend integration test was not executed in this environment due to missing test dependencies (the test harness dependency httpx / test client environment was not available). ⛔

---

Codex Task