[codex] Broaden nr-app test coverage

[guaka]

Summary

Broaden nr-app coverage beyond the browser-specific tests by adding shared app test infrastructure and focused Jest coverage for high-value general app workflows.

What Changed

• Added shared renderWithProviders() and a configurable real Redux store factory for screen/component tests.
• Added reusable fixtures for Nostr events, map notes, Trustroots profile events, plus codes, and relay data.
• Added workflow/component tests for app routing, welcome/onboarding states, map list tabs, notification subscribe/unsubscribe, and add-note publish validation.
• Added reducer/selector tests for events, keystore, notifications, and settings.
• Added coverage scripts and ignored generated coverage output.

Validation

• pnpm --filter nr-app exec jest --watchman=false passed: 25 suites, 106 tests.
• pnpm --filter nr-app exec jest --watchman=false --coverage passed.
• pnpm test:app:coverage passed.
• Scoped lint for the new/changed files passed.
• Full pnpm --filter nr-app lint still reports pre-existing unrelated issues in current app files.

[guaka]

Folded the useful test coverage from this draft into #227 and updated nr-app-test-suite instead.