feat(settings): AI tab and email preferences with a local send schedule - #1531

🟢 Confidence 7/10 · likely safe to merge
The scheduling change moves every subscriber's digest time and is pinned by zone/DST tests, but the no-primary-email save path from F1 is still a silent no-op.
_{quality 98/100 · 1 note · tests covered · risk medium · 2/2 new units observable}

Moves auto-triage onto the AI tab with provider cards and adds email preferences with a local day/hour/zone digest schedule (new send_hour column, backend-validated, isDigestDue + a 6-day claim window). Logic is well pinned by tests; the only open defect is the silent no-op save for a user with no primary email.

• isDigestDue decides sends on the subscriber's local day/hour/zone
• Digest claims now guard on a 6-day resend cutoff, not UTC midnight
• send_hour column (default 9) plus day/hour/zone validation on upsert
• Auto-triage limits move to the AI tab behind SettingsSaveBar

Before merge

• Migration · Check it is safe on production data and with the code still deployed · packages/db/drizzle/20261017080931_digest_send_hour/migration.sql

Still open from earlier reviews

• 🔵 Note · F1 · Save is a silent no-op for a user with no primary email · apps/web/src/components/account/email-preferences-section.tsx:121

Production impact

_{a06d415 · Updated on every push. Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}