Implement full-stack Plex integration with authentication, scanning, and extras checking

[Copilot]

• Analyze the reported issues in Plex integration
• Fix baseUrl construction in plex.service.ts (remove extra slash)
• Add X-Plex-Client-Identifier header to polling requests in auth.py
• Update API endpoint to accept client identifier as query parameter
• Update frontend component to store and pass client identifier
• Test the fixes to ensure frontend builds successfully

Issues Fixed

1. URL Construction: Fixed the extra / in baseUrl construction in plex.service.ts - changed from environment.apiUrl + '/plex' to environment.apiUrl + 'plex'

2. Missing Header: Added required X-Plex-Client-Identifier header to Plex polling requests:

   • Updated poll_for_token() function to accept client_identifier parameter
   • Modified API endpoint to accept client identifier as query parameter
   • Updated frontend service to pass client identifier in polling requests
   • Updated frontend component to store and manage client identifier state

Technical Changes

• Backend: Modified auth.py to include client identifier header in Plex API calls
• API: Updated polling endpoint to accept client_identifier query parameter
• Frontend Service: Updated pollForToken() method to include client identifier
• Frontend Component: Added client identifier state management and proper parameter passing

The Plex authentication flow should now work correctly with proper API communication.

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[nandyalu]

@copilot

Some things are not working.

1. First things first, the baseUrl in plex.service.ts has an extra \ as the apiUrl already has an ending slash.
2. I tried changing that and then getting this error on trying to connect to Plex. Looks like we need to send client identifier for poll to work:

2025-09-18T04:27:31+0000 [ERROR|auth|L107]: PlexAuth: Failed to poll token from Plex: 400 - {"errors":[{"code":1000,"message":"X-Plex-Client-Identifier is missing","status":400}]}
ERROR: Failed to poll token from Plex: 400 - {"errors":[{"code":1000,"message":"X-Plex-Client-Identifier is missing","status":400}]}
2025-09-18T04:27:31+0000 [ERROR|auth|L136]: PlexAuth: Unexpected error during token polling: Failed to poll token from Plex: 400
ERROR: Unexpected error during token polling: Failed to poll token from Plex: 400
2025-09-18T04:27:31+0000 [ERROR|plex|L122]: PlexAPI: Failed to poll Plex token: Failed to poll token from Plex: 400
ERROR: Failed to poll Plex token: Failed to poll token from Plex: 400
INFO:     172.17.0.1:52849 - "GET /api/v1/plex/auth/poll/m91bdyoej1622un33bmia0sre" 400 Bad Request 477.44ms

[Copilot]

@copilot

Some things are not working.
...

Fixed both issues in commit 84da1b0:

1. URL Construction: Removed the extra / in plex.service.ts baseUrl construction
2. Missing Client Identifier: Added X-Plex-Client-Identifier header to Plex polling requests

The backend now properly accepts the client identifier as a query parameter and includes it in the Plex API headers. The frontend has been updated to store and pass the client identifier throughout the authentication flow.

The Plex authentication should now work correctly without the 400 error.