feat: generate-a-auth-cookie-on-oauth-succesful-logins

[Zaimwa9]

Thanks for submitting a PR! Please check the boxes below:

• I have added information to docs/ if required so people know about the feature!
• I have filled in the "Changes" section below?
• I have filled in the "How did you test this code" section below?
• I have used a Conventional Commit title for this Pull Request

Changes

Allow Google and Github OAuth with cookie login.

• Set a cookie when cookie_auth is enabled and oauth succesful

How did you test this code?

• Manually
• ⚠️ couldn't test github due to redirect_uri not set for local

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

3 Skipped Deployments

Name	Status	Preview	Comments	Updated (UTC)
docs	⬜️ Ignored (Inspect)	Visit Preview		Jul 2, 2025 4:06pm
flagsmith-frontend-preview	⬜️ Ignored (Inspect)	Visit Preview		Jul 2, 2025 4:06pm
flagsmith-frontend-staging	⬜️ Ignored (Inspect)	Visit Preview		Jul 2, 2025 4:06pm

[github-actions]

Docker builds report

Image	Build Status	Security report
ghcr.io/flagsmith/flagsmith-api-test:pr-5670	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-e2e:pr-5670	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-frontend:pr-5670	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-api:pr-5670	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith:pr-5670	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-private-cloud:pr-5670	Finished ✅	Results ✅

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.77%. Comparing base (de7c278) to head (01d50ce).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5670   +/-   ##
=======================================
  Coverage   97.77%   97.77%           
=======================================
  Files        1253     1253           
  Lines       44242    44279   +37     
=======================================
+ Hits        43256    43293   +37     
  Misses        986      986           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[emyller]

Solution looks good with a slight re-shaping. Also please add tests to cover the settings.COOKIE_AUTH_ENABLED case. Thanks!