test(logger): cover logError DEV/PROD/Sentry branches

[tanishxdev]

What does this PR do?

Adds src/lib/logger.test.ts, unit-testing logError across all four DEV/PROD/Sentry code paths.

Why?

logError is the app's single error-logging chokepoint but had zero test coverage, so a regression here could silently swallow errors without anyone noticing.

Closes #51

How was this tested?

Added four cases in src/lib/logger.test.ts, following the style of src/lib/scoring.test.ts:

• DEV: logs to console.error with the [context] prefix.
• PROD + window.Sentry present: calls window.Sentry.captureException(err, { tags: { context } }).
• PROD + Sentry throws: falls back to console.error (catch block), verified call order with toHaveBeenNthCalledWith.
• PROD + no Sentry: logs to console.error.

window is stubbed per-test with vi.stubGlobal('window', {}) since the suite runs under environment: 'node' (per vitest.config.ts) with no real DOM global. import.meta.env.DEV/PROD are set directly as booleans (via a typed cast) rather than vi.stubEnv, since stubbing them as strings didn't coerce to real booleans in this setup and caused false-positive branch execution.

Ran locally:

Test Files  17 passed (17)
     Tests  225 passed (225)

• npm run test — 225/225 passing (17 test files, including the new 4 in logger.test.ts)
• npm run lint — clean, no errors or warnings
• npm run validate — all question banks valid (pre-existing warnings in saa-c03 unrelated to this change)

Checklist

• npm run build passes locally — could not fully verify; local build fails at static-path generation with Missing Supabase environment variables, unrelated to this change (no .env credentials configured locally)
• npm run lint passes locally
• npm run test passes locally
• npm run validate passes locally (only if you touched src/data/**/*.json) — N/A, no data files touched (ran anyway, passes)
• No new third-party dependencies

Screenshots (UI changes only)

N/A — test-only change, no UI impact.