feat: add spotify oauth adapter

[devin-ai-integration]

Add Spotify OAuth adapter implementing authorization code flow.

• Implements standard OAuth2 authorization code flow with authorization code grant type
• Supports essential scopes:
  • user-read-private (basic profile)
  • user-read-email (email access)
  • playlist-read-private (playlist access)
  • user-library-read (saved content)
• Follows existing adapter pattern used by other OAuth providers
• Configures Spotify-specific OAuth endpoints:
  • Authorization: https://accounts.spotify.com/authorize
  • Token: https://accounts.spotify.com/api/token

Link to Devin run: https://app.devin.ai/sessions/b8acf68438ab49fd86868b5d2331d63f

[devin-ai-integration]

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[changeset-bot]

🦋 Changeset detected

Latest commit: c1614b8

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@openauthjs/openauth	Patch
nextjs	Patch

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[thdxr]

don't specify the scopes let the user pass through