fix: make player fullscreen mode discoverable

[Santirv17]

The player fullscreen layout was only accessible through ?fullscreen=true, making it difficult for users to discover. This PR exposes the fullscreen control in the normal desktop player and changes to the native Fullscreen API for handling.

• Shows the fullscreen button in the normal desktop player view
• Updates the fullscreen search parameter while preserving other player search parameters
• Returns to the normal player layout when fullscreen is closed through the button, Esc, or F11
• Removes the unused react-fullscreen-crossbrowser dependency and redundant fullscreen context state
• Adds Cypress test for entering, exiting, external fullscreen changes, search parameter handling, and direct fullscreen URLs.
• Updates shortcut and auto-login search-parameter tests, affected by removed dependency, to use shuffle instead of the browser-dependent fullscreen parameter

close #1253
close #1218

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud