feat: add booking confirmation email invitations

[TechAaroorian]

Summary

Adds transactional booking confirmation emails using Resend and React Email.

Changes

• Send a confirmation email after a booking is created
• Render a reusable React Email confirmation template
• Attach an ICS calendar invitation
• Store a stable calendar UID with the booking
• Format meeting time using the guest timezone
• Generalize meeting-provider information
• Display booking and email-delivery outcomes separately
• Preserve a successful booking when email delivery fails
• Add tests for successful and failed email delivery

User experience

After confirming a booking, the guest sees:

• Authoritative booking confirmation
• Meeting details
• Email delivery status
• A warning when the booking succeeded but email delivery failed

Reliability

Email delivery occurs only after booking creation succeeds. A Resend failure does not roll back or hide the confirmed booking.

Validation

• Booking Server Action tests
• Booking UI flow tested manually
• Confirmation email received successfully
• ICS invitation received with the email

Notes

This feature provides immediate email delivery. Persisted notification state and background retry processing remain planned architecture work.

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	99.06%	106 / 107
🔵	Statements	98.16%	107 / 109
🔵	Functions	100%	13 / 13
🔵	Branches	82.14%	46 / 56

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
apps/app/app/actions/booking.ts	94.87%	70.58%	100%	97.36%	151, 164

Generated in workflow #22 for commit 1b95eeb by the Vitest Coverage Report Action