Add websocket routing support

[Suhaibinator]

Summary

• add a WebSocketRouteConfig and handler wrapper so websocket endpoints reuse the router middleware pipeline
• document websocket usage and add README links for the new capability
• cover websocket registration with an echo test case

Testing

• go test ./...

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Codex Task

[codecov]

Codecov Report

❌ Patch coverage is 80.76923% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.45%. Comparing base (519a7e3) to head (cf3487c).

Files with missing lines	Patch %	Lines
pkg/router/websocket.go	56.52%	8 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #101      +/-   ##
==========================================
- Coverage   97.06%   96.45%   -0.61%     
==========================================
  Files          18       19       +1     
  Lines        2382     1777     -605     
==========================================
- Hits         2312     1714     -598     
+ Misses         57       48       -9     
- Partials       13       15       +2     

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

WebSocket upgrade fails when timeout middleware is enabled

Because WebSocket routes are run through wrapHandler, any non-zero Global/SubRouter/route timeout adds the timeout middleware, which replaces the http.ResponseWriter with mutexResponseWriter that does not implement http.Hijacker. The gorilla/websocket.Upgrader.Upgrade call here requires a Hijacker and will return websocket: response does not implement http.Hijacker, so WebSocket endpoints cannot upgrade once timeouts (or any similar middleware that wraps the writer) are configured.

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