feat: implement multi-factor authentication (MFA) setup and verification flow

- Add SecurityPage component for managing MFA settings, including enrollment and verification.
- Create MfaLoginGate to handle MFA verification state during login.
- Develop MfaVerificationPopup for user input of verification codes.
- Implement VerifyMfaPage for the MFA verification process after login.
- Introduce reusable VerificationCodeInput component for entering verification codes.
- Integrate Supabase MFA API for managing factors and verification.
- Add loading states and error handling for a better user experience.

backend/oss-migrations/20260606_oss_schema_diff.sql

@@ -10,6 +10,7 @@
 
 alter table public.user_profiles
   add column if not exists title_model text,
+  add column if not exists mfa_on_login boolean not null default false,
   add column if not exists quote_model text;
 
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