fix: forgot-password mailer errors and SMTP timeouts

[habiibullahm]

Summary

• Return 503 when the mailer is not configured (production) or SMTP/Resend send fails, instead of a silent success
• Add 10s SMTP connectionTimeout / greetingTimeout / socketTimeout so Render does not hang ~2 minutes on Gmail
• Expose mailerConfigured on /health, warn at boot in production, and clarify UI “Mailer error” copy

Test plan

• Integration tests for SMTP success + SMTP failure → 503
• After merge: redeploy Render API
• Confirm /api/v1/health includes mailerConfigured
• Forgot password for a real account (or expect fast 503 if Gmail SMTP is blocked — prefer Resend on Render)