Add skip_setup_flow flag to oauth

[lordbagel42]

Summary of the problem

Hackatime requires setting up a code editor before connecting to Stardance, in addition the homepage is very coding centric and discouraging. Homepage changes have been moved to #1456

Describe your changes

When skip_setup_flow is passed into the hackatime oauth it skips to step4 of the WakatimeSetup flow & showcases a banner that setting up a code editor was skipped. This way, everybody still has to agree to the rules.

This PR is blocking for hackclub/stardance#702

Screenshots / Media

Video showcasing Stardance using the new flag:
https://github.com/user-attachments/assets/d14be4ae-9b8a-4ecf-a103-22de7d8b05ab

[greptile-apps]

Greptile Summary

This PR adds a shortened Wakatime setup path for OAuth flows that pass skip_setup_flow. The main changes are:

• Preserves skip_setup_flow in return data across sign-in redirects.
• Sends skipped setup users directly to the final Wakatime setup step.
• Adds a skipped setup banner and Fair Play acknowledgment UI before continuing.
• Keeps the OAuth return URL available for the final continue button.

Confidence Score: 5/5

The changes are narrowly scoped to preserving an OAuth flag and adjusting the setup flow UI around that flag.

No code issues were identified in the reviewed changes, and the implementation appears consistent with the described setup-skip behavior.

T-Rex Logs

What T-Rex did

• Executed the OAuth skip flow repro script to validate the integration scenario; observed base and head checkout tests exit with code 127 due to missing Ruby.
• Explored the Waketime skip UI flow by reviewing end-to-end renders; the after-state shows a skipped-editor banner and Fair Play Policy gate, and the final action becomes enabled after agreeing.

_{Ran code and verified through T-Rex}

_{Reviews (7): Last reviewed commit: "remove whitespace + remove debug log + c..." | Re-trigger Greptile}

[skyfallwastaken]

@greptileai one final check por favor?

(bagel - lgtm but I'd like to double check :pf:)

stale