Send email digests on cronjobs for emails that failed to send

[TheCactusBlue]

---

[!IMPORTANT] Add cron job and route handler to send email digests for failed emails to project owners.

• Cron Job:
  • Adds a cron job in vercel.json to trigger /api/latest/cron/send-email-digest daily.
• Route Handler:
  • New route handler GET in route.ts to send email digests of failed emails to project owners.
  • Validates requests using CRON_SECRET from environment variables.
  • Fetches failed emails from the last 24 hours and groups them by project.
  • Sends email digests to primary contact channels of project users.
• Email Configuration:
  • Exports getEmailConfig in emails.tsx for use in the new route handler.
• Testing:
  • Adds tests in email-digest.test.ts to verify email digest sending behavior for failed and non-failed emails.

^{This description was created by for a5cbd6f7193352df324cbcc26352408830fca954. It will automatically update as commits are pushed.}

[vercel[bot]]

Deployment failed with the following error:

The `vercel.json` schema validation failed with the following message: `crons` should be array

Learn More: https://vercel.com/docs/concepts/projects/project-configuration

[vercel[bot]]

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[recurseml[bot]]

😱 Found 5 issues. Time to roll up your sleeves! 😱

[vercel[bot]]

Deployment failed with the following error:

The `vercel.json` schema validation failed with the following message: `crons[0]` missing required property `schedule`

Learn More: https://vercel.com/docs/concepts/projects/project-configuration

[N2D4]

@TheCactusBlue this one's also still waiting for you

[zeropath-ai[bot]]

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Reply to this PR with @zeropath-ai followed by a description of what change you want and we'll auto-submit a change to this PR to implement it.

[zeropath-ai[bot]]

Some new issue(s) might be present. Please use the following link(s) to view them:

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Reply to this PR with @zeropath-ai followed by a description of what change you want and we'll auto-submit a change to this PR to implement it.