fix(web): render resilient inbox rows

[Tutitoos]

Related issue

Closes #188

Plan reference

Phase 3 — Gmail and web: inbox and reading usability; follow-up from the complete UI quality audit.

Summary

Keeps inbox rows complete, legible, and actionable when provider metadata is missing, and localizes row actions consistently with the selected language.

Changes

• Resolve localized sender, subject, and preview fallbacks once per row.
• Replace the dangling preview separator with a deliberate empty-preview state.
• Reuse resilient identity text across open, selection, star, importance, read, and context-menu labels.
• Localize quick actions and the contextual menu in English and Spanish.
• Cover missing subject, preview, and sender metadata in the six-viewport inbox test.

Validation

• Relevant automated checks pass

• Manual verification completed where needed

• bun run --cwd apps/web test: 50 tests passed.

• bun run --cwd apps/web typecheck: passed.

• bun run --cwd apps/web build: passed; existing bundle-size and Tauri dynamic-import warnings remain.

• go test ./internal/modules/translations: passed.

• bun run --cwd apps/web test:e2e -- tests/inbox.spec.ts: 6 viewport projects passed after correcting a detected accessible-name regression.

• Codex integrated browser audit on authenticated production: desktop and mobile geometry had no horizontal overflow; labels, More, context, account, language, and conversation states were exercised before implementation.

Risks and rollback

The change is limited to web row presentation and translation keys. Revert the single commit to restore the prior rendering; no message or provider data is changed.

Checklist

• The PR has one coherent scope
• The branch and Closes reference identify the same primary issue
• The issue acceptance criteria are satisfied
• No secrets, credentials, personal data, or unintended files are included
• Documentation and tests are updated when applicable
• Breaking changes are explicitly documented