feat: add account deletion feature (#85)

* feat: add account deletion feature

- Add DELETE /auth/me endpoint to delete user account and all data
- Add deleteAccount() method to AuthContext
- Add Delete Account button with confirmation modal in UserProfile
- Add danger zone styling (.btn-danger, .profile-danger-zone)
- Add i18n translations for EN and DE
- Add backend tests for account deletion endpoint
- Add timeout settings to frontend vitest.config.ts
- Reduce CI timeout for frontend tests (10min -> 5min)

* fix: improve delete account section layout

- Make profile modal scrollable with max-height
- Add proper horizontal margin to danger zone
- Align delete section with form content

* fix: use ConfirmModal component for delete account dialog

- Replace inline modal with existing ConfirmModal component
- Ensures consistent button styling across all modals
- Add UI consistency rule to AGENTS.md and copilot-instructions.md

* fix: consistent styling for delete account section

- Remove warning text (users know what delete means)
- Remove border-bottom from danger zone title (section has border-top)
- Update copilot-instructions and AGENTS.md with stricter UI consistency rules
- Remove unused deleteAccountHint i18n keys

* chore: remove pre-push test hook (CI handles tests)

Tests were running twice - in pre-push hook and GitHub CI.
Removing local pre-push tests since CI provides authoritative test results.
Use 'npm test' manually before pushing if you want local feedback.

.github/copilot-instructions.md

@@ -500,6 +500,7 @@ Example: `5-0-1735344000000` = Medication 5, Blister 0, timestamp
 - **API responses**: Return objects directly, Fastify serializes to JSON
 - **Environment**: Copy `.env.example` → `.env`, secrets must be 10+ chars
 - **i18n**: All UI text via `t('key')` function, translations in `frontend/src/i18n/*.json`
+- **UI Consistency**: Always use existing components for modals, buttons, and forms. For confirmation dialogs, use `ConfirmModal` component. Never create inline modals with custom button styling - all UI elements must match the existing design system. When adding new sections to existing components, ensure font sizes, spacing, margins, and button styles match exactly with other sections. Check existing CSS classes before creating new ones.
 
 ## Database Schema Changes (IMPORTANT: Backward Compatibility!)
 

.github/workflows/update-test-badges.yml

@@ -54,7 +54,7 @@ jobs:
       - name: Run frontend tests and capture count
         id: frontend-tests
         working-directory: frontend
-        timeout-minutes: 10
+        timeout-minutes: 5
         env:
           CI: true
         run: |