Summary of Changes

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This pull request streamlines the process of serving the GraphiQL interface by integrating its detection directly into the HTTP content negotiation pipeline. It introduces a specific ResponseMode for GraphiQL and modifies the negotiation logic to prioritize text/html for GET requests, ensuring that clients requesting HTML content are correctly served the GraphiQL IDE. This change simplifies the codebase and makes the GraphiQL rendering more consistent with standard content type handling.

Highlights

• Refactored GraphiQL Rendering Logic: The mechanism for determining when to serve the GraphiQL interface has been overhauled, moving from a separate can_accept_http check to an integrated ResponseMode negotiation.
• New ResponseMode::GraphiQL: A dedicated GraphiQL variant has been added to the ResponseMode enum, explicitly representing the intent to render the GraphiQL IDE.
• Prioritized text/html Negotiation for GET Requests: The content type negotiation now considers text/html with higher priority for GET requests, allowing clients that prefer HTML to automatically receive GraphiQL.
• Removal of can_accept_http: The can_accept_http helper function and its associated logic have been removed, as its functionality is now subsumed by the enhanced content negotiation.

✅ k6-benchmark results

     ✓ response code was 200
     ✓ no graphql errors
     ✓ valid response structure

     █ setup

     checks.........................: 100.00% ✓ 235578      ✗ 0    
     data_received..................: 6.9 GB  229 MB/s
     data_sent......................: 92 MB   3.1 MB/s
     http_req_blocked...............: avg=2.82µs   min=647ns   med=1.7µs   max=5.04ms   p(90)=2.55µs  p(95)=2.97µs 
     http_req_connecting............: avg=375ns    min=0s      med=0s      max=1.55ms   p(90)=0s      p(95)=0s     
     http_req_duration..............: avg=18.65ms  min=1.68ms  med=17.7ms  max=107.5ms  p(90)=25.71ms p(95)=29.01ms
       { expected_response:true }...: avg=18.65ms  min=1.68ms  med=17.7ms  max=107.5ms  p(90)=25.71ms p(95)=29.01ms
     http_req_failed................: 0.00%   ✓ 0           ✗ 78546
     http_req_receiving.............: avg=136.86µs min=28.29µs med=45.66µs max=35.97ms  p(90)=83.28µs p(95)=395.9µs
     http_req_sending...............: avg=23.48µs  min=4.85µs  med=10.25µs max=20.17ms  p(90)=15.49µs p(95)=22.58µs
     http_req_tls_handshaking.......: avg=0s       min=0s      med=0s      max=0s       p(90)=0s      p(95)=0s     
     http_req_waiting...............: avg=18.49ms  min=1.6ms   med=17.57ms max=106.95ms p(90)=25.44ms p(95)=28.66ms
     http_reqs......................: 78546   2613.353808/s
     iteration_duration.............: avg=19.09ms  min=5.84ms  med=18.02ms max=249.44ms p(90)=26.16ms p(95)=29.47ms
     iterations.....................: 78526   2612.688375/s
     vus............................: 50      min=50        max=50 
     vus_max........................: 50      min=50        max=50 

🐋 This PR was built and pushed to the following Docker images:

Image Names: ghcr.io/graphql-hive/router

Platforms: linux/amd64,linux/arm64

Image Tags: ghcr.io/graphql-hive/router:pr-705 ghcr.io/graphql-hive/router:sha-decd0a4

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