fix(embed): include calOrigin for non-default cloud domains

[abdulbaqui17]

Summary

• fix embed snippet generation to include calOrigin for non-default Cal cloud domains (for example app.cal.eu)
• keep omitting calOrigin for default cloud origins (https://app.cal.com and https://cal.com)
• add regression tests for origin detection logic, including trailing slash normalization

Why

Published @calcom/embed-react defaults to app.cal.com. For users on non-default cloud domains like app.cal.eu, snippets generated without calOrigin can resolve iframe URLs to the wrong TLD and return 404.

Testing

• TZ=UTC yarn vitest run packages/features/embed/lib/EmbedCodes.test.ts (run in local workspace where dependencies are already available)

Fixes #28443

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Summary by cubic

Fixes embed snippets to include calOrigin for non-default cloud domains and preserves original duration in the reschedule flow. Also updates attendee emails to use the organizer’s time format when the attendee doesn’t have one set.

• Bug Fixes
  • Embed: include calOrigin for non-default cloud origins (e.g., app.cal.eu); omit for https://app.cal.com and https://cal.com; handles trailing slashes; adds regression tests in packages/features/embed/lib/EmbedCodes.test.ts.
  • Reschedule: pass duration based on the original booking length; keeps dynamic durations; adds tests for reschedule link and duration fallback.
  • Emails: fallback to organizer timeFormat in AttendeeScheduledEmail when attendee preference is missing; adds test coverage.

^{Written for commit 90a1143. Summary will update on new commits.}

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[cubic-dev-ai]

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