feat(email): unsubscribe from digest emails without signing in - #1262

🟢 Confidence 5/5 · safe to merge
The new test pins all three MAPLE_API_BASE_URL branches and env.ts itself is unchanged since the earlier review.
_{quality 100/100 · no findings · tests covered · risk low}

This commit only adds coverage for appUrlsEnv's MAPLE_API_BASE_URL branch inside packages/infra/src/env.test.ts; the env group it tests is unchanged. Safe to merge.

• Test pins appUrlsEnv's derived MAPLE_API_BASE_URL from domains.api, the provider override, and the api.maple.dev default

Fixed since the last review

• ✅ F2 · appUrlsEnv's new MAPLE_API_BASE_URL branch is untested

_{23fc5db · Updated on every push. Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}