feat: Implement email OTP authentication

[HarshMN2345]

What does this PR do?

Add email OTP as primary login method with separate verification page, proper Appwrite SDK integration, and dynamic UI switching.

Test Plan

Related PRs and Issues

(If this PR is related to any other PR or resolves any issue or related to any issue link all related PR and issues here.)

Have you read the Contributing Guidelines on issues?

yes

Summary by CodeRabbit

• New Features

  • Passwordless email sign-in with a dedicated OTP verification page, verify and resend flows.

• UX Changes

  • Form toggles between password and passwordless modes; password is now optional and email input no longer autofocus.
  • Action button text/behavior adapts to chosen mode.

• Reliability

  • Improved notifications, error handling, resend feedback, and safer redirect handling.

• Refactor

  • Centralized resend cooldown component reused in verification and modal UIs.