[bug]: test email not sending while setting up SMTP

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

When setting up SMTP for the first time under Instance Admin (God Mode) → Settings → Email, if you fill in the SMTP fields and click "Send test email" without clicking "Save Changes" first, the request fails with a 500 error instead of a validation message.

Backend log shows:
ValueError: invalid literal for int() with base 10: ''
at plane/license/api/views/configuration.py, line 110, in post
port=int(EMAIL_PORT)

The test-email endpoint (/api/instances/email-credentials-check/) appears to be reading EMAIL_PORT (and presumably the other SMTP fields) from the last saved instance configuration rather than the values currently typed into the form. Since nothing had been saved yet, EMAIL_PORT was an empty string, and int('') threw an unhandled ValueError, causing a 500.

What I expected: either the test should validate against the unsaved form values (so first-time setup works without a separate save step), or if it's intentional that test-email only works against saved config, the UI should block the test / show a clear "please save your settings first" message instead of silently failing with a 500.

Steps to reproduce

1. Go to Instance Admin (God Mode) → Settings → Email on a fresh instance with no email config saved yet.
2. Fill in SMTP Host, Username, Password, Port, and Sender Email.
3. Without clicking "Save Changes", click "Send test email".
4. Request to POST /api/instances/email-credentials-check/ returns 500.
5. Backend logs show ValueError: invalid literal for int() with base 10: '' at configuration.py line 110.
6. Click "Save Changes", then click "Send test email" again — this time it succeeds.

Environment

Production

Browser

Google Chrome

Variant

Self-hosted

Version

v1.3.1