fix(settings): preserve the OAuth connect payload

[RaresKeY]

Summary

This replaces #5652, which GitHub closed during the repository transfer and fork-network separation. The branch has been rebuilt on the current dev history; the implementation scope is unchanged.

Preserve the selected SMTP security mode and display name when the Email tab's Google Connect button first saves an account. This keeps the saved SMTP port and security mode consistent instead of relying on a server-side default that can disagree with the form.

The change only adds two existing form values to the account payload. It does not change rendering, account layout, or the OAuth redirect flow.

Target branch

• This PR targets dev, not main.

Linked Issue

Fixes #5647

Part of #5637

Type of Change

• Bug fix (non-breaking — fixes a confirmed issue)
• New feature (non-breaking — adds new behaviour)
• Breaking change (changes or removes existing behaviour)
• Refactor / cleanup (behaviour unchanged)
• Documentation only
• CI / tooling / configuration

Checklist

• I searched open issues and open PRs — this Connect-payload bug is not already tracked.
• This PR targets dev.
• My changes are limited to two existing form fields and focused regression coverage.
• I ran the app end-to-end. Source-level regression tests and JavaScript syntax checks pass; a live Google callback was not available.

How to Test

1. Run:

   python -m pytest -q tests/test_email_oauth_connect_smtp_security.py
   node --check static/js/settings.js

2. In the Email account form, select SMTP port 587 with STARTTLS and enter a display name.

3. Click Connect with Google and inspect the account-creation request.

4. Verify smtp_security and display_name match the form and persist on the saved account.

Current-dev isolated validation passes 37 focused/adjacent tests, JavaScript syntax, and diff checks.

Visual / UI changes

N/A — the existing form renders identically; only its request payload changes.

Screenshots / clips

N/A — no visual rendering change.

[alteixeira20]

Audited at exact head fb31743. This focused fix preserves the existing display-name and SMTP-security form values in the Google OAuth account-creation payload. The change is limited to two existing fields with focused regression coverage. Required CI and security checks pass, and there are no blocking comments or unresolved review threads.