fix(a11y): label dialogs and mobile sidebar controls

[devswha]

Summary

• expose Settings and project creation as labelled modal dialogs
• add translated names to close, mobile refresh, and mobile create-project controls
• close dialogs with Escape and restore focus to the opening control
• focus the dialog surface on open for predictable keyboard navigation

Verification

• static accessibility markup tests: 2/2
• npm run typecheck
• npm run lint
• npm run build

Keyboard behavior will also be exercised in the integrated in-app browser QA run.

[devswha]

Actual browser QA (2026-07-22): Settings and Create New Project expose named dialogs with translated Close controls. Pressing Escape closed each dialog and restored focus to its exact trigger. Mobile refresh/create controls expose translated accessible names.