feat: add per-email tracking override to /v1/send

[chamby]

Description

Adds an optional tracking boolean to POST /v1/send that overrides the project's TrackingMode for a single email. Omitted → project mode applies exactly as today; false/true → wins for that send.

Implementation follows the existing plumbing:

• Nullable trackingOverride column on emails (+ migration) so the worker sees the override at send time
• EmailService.sendEmail: email.trackingOverride ?? shouldTrackEmail(...) — the only behavioral change; campaigns and workflows are untouched
• tracking: z.boolean().optional() in ActionSchemas.send, passed through Actions.send → sendTransactionalEmail
• OpenAPI spec + tracking guide updated

Same constraint as MARKETING_ONLY: only effective when SES_CONFIGURATION_SET_NO_TRACKING is configured; when it isn't, the override is silently ignored. If you'd rather surface a warning in the response (or prefer the internal-header approach from the issue), happy to rework.

Type of Change

• feat: New feature (MINOR version bump)

Testing

• 7 new tests in EmailService.test.ts: override beats project mode in both directions, null falls back to project mode, persistence from sendTransactionalEmail, and schema accept/reject cases
• Full EmailService suite passes (51 tests); yarn build --filter=api and lint clean
• Migration validated by the test harness applying it to worker databases

Checklist

• PR title follows conventional commits format
• Code builds successfully
• Tests pass locally
• Documentation updated (if needed)

Related Issues

Closes #432

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Prepared by Claude (AI assistant) acting on behalf of Matthew Chambers (@chamby), who reviewed the approach.

🤖 Generated with Claude Code

[chamby]

Heads-up on a gap found while verifying this feature against a live v0.12.0 deployment: the original diff only applied the override in EmailService.sendEmail, but the path /v1/send actually takes is API → queue → jobs/email-processor.ts, which has its own copy of the tracking decision. The override was stored but never applied — a silent no-op, confirmed by SES still emitting Open events for opted-out sends.

Pushed a fix in ab2ad0a:

• email-processor.ts now applies email.trackingOverride ?? EmailService.shouldTrackEmail(...) (the one behavioral line)
• Extracted the inline Worker callback to an exported processEmailJob so the worker send path is directly testable — pure extraction, no behavior change; the diff is mostly re-indentation (git diff -w shows the real changes)
• 3 new worker-path tests covering override-wins in both directions and null-falls-back; full API suite passes (769 tests)

Might be worth unifying the two send paths at some point so decisions like this live in one place — left that alone here to keep the PR focused.

Posted by Claude on behalf of @chamby.