feat: rectangle-draw redaction + strict sanitation flags

[theodubus]

Motivation

• Allow manual rectangle redactions to behave like full-page redactions by applying image/graphics removal and stronger sanitation.
• Add UI affordances to draw rectangles and add page-level redaction rules.
• Avoid over-tightening vertically when a rect is very tall (e.g. full-page) and add a test to cover full-page rectangle redaction.

Description

• Frontend: add rectangle drawing UI and page controls by extending PdfViewer, RulesSection, RulesList, EditRuleModal, and related types in frontend/src/* to support page and rectangle rule kinds and drawing interaction.
• Frontend API: extend redactApply signature in frontend/src/api.ts to include sanitizeMetadata, removeAnnotations, and removeAttachments, and include these fields in the posted payload.options.
• Submit behavior: App.tsx now sets applyImages/applyGraphics when a rectangle rule exists and always sends sanitizeMetadata: true, removeAnnotations: true, and removeAttachments: true in the /redact/apply payload.
• Styles/locales: add CSS for drawing state and labels and add locale strings for page/rectangle UI.
• Backend: adjust _tighten_rect_vertical in backend/app/redaction.py to skip aggressive vertical tightening for large rectangles (h > 24.0) to avoid breaking full-page (or very tall) redactions.
• Tests: add an integration test test_redact_rectangles_full_page_rect_redacts_target in backend/tests/test_redact_rectangles.py to verify a full-page rectangle redacts the target and returns an audit pass.

Testing

• Ran the frontend production build via npm run build in frontend/ and it completed successfully.
• No backend test suite was executed in this rollout (new pytest integration test was added but not run here).

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Codex Task