A11y/tiptap button labels

[amazingphilippe]

Summary | Résumé

This pull request refactors the rich text editor's toolbar and tooltips to enhance accessibility. It centralizes all editor UI labels and keyboard shortcuts (with platform-specific variants) into a new localization module, replaces ad-hoc label definitions with context-based translation, and updates the Cypress tests to accommodate these changes. Additionally, it improves tooltip accessibility and updates the test suite to check for both English and French UI labels.

Test instructions | Instructions pour tester la modification

• Label toggles: Verify each toolbar button shows either "Apply {Label}" or "Remove {Label}"
• aria-pressed: Confirm aria-pressed is false → true → false when applying/removing formatting for every button.
• Live region announcements: After applying, live region contains "applied"; after removing, contains "removed".
• Tooltips: Hover each toolbar button and assert the tooltip box appears and the tooltip label is not empty.
• Toolbar keyboard focus: Press Alt+F10 to focus the toolbar; assert initial focus (H1) and that arrow keys move focus forwards/backwards and restore remembered position.
• Shortcut toggles: For each keyboard shortcut (e.g., Mod+Alt+1 for Heading, Mod+b for Bold), verify the corresponding button toggles aria-pressed.
• Link modal: Press Mod+K to open the link modal; verify it is visible and that Escape closes it.

[github-actions]

🧪 Review environment

https://kxcgmv4z7opacax3usdcjxwmqq0ychfq.lambda-url.ca-central-1.on.aws/

[andrewleith]

A couple of comments below.

[andrewleith]

LGTM!