feat(caching): Implement cache hit detection and response header management

- Added functionality to mark responses as cache hits to prevent incorrect X-Cache headers.
- Introduced setCacheHitFlag function to traverse response writer wrappers and set cache hit flag.
- Updated cachingResponseWriter to manage cache hit state and adjust X-Cache header accordingly.
- Enhanced ProcessRequest and ProcessResponse methods to utilize new caching logic.

feat(extension): Introduce ResponseWriterWrapper and ResponseFinalizer interfaces

- Added ResponseWriterWrapper interface for extensions to wrap response writers.
- Introduced ResponseFinalizer interface for finalizing responses after processing.

refactor(manager): Improve response writer wrapping and finalization

- Updated Manager.Handler to wrap response writers through all enabled extensions.
- Implemented finalization of response writers after processing requests.

test(caching): Add comprehensive integration tests for caching behavior

- Created caching_test.go with tests for cache hit/miss, TTL expiration, pattern-based caching, and more.
- Ensured that caching logic works correctly for various scenarios including query strings and error responses.

test(routing): Add integration tests for routing behavior

- Created routing_test.go with tests for route priority, case sensitivity, default routes, and return directives.
- Verified that routing behaves as expected with multiple regex routes and named groups.

go/internal/extension/extension.go

@@ -109,3 +109,15 @@ type ExtensionConfig struct {
 
 // ExtensionFactory is a function that creates an extension from config
 type ExtensionFactory func(config map[string]interface{}, logger *logging.Logger) (Extension, error)
+
+// ResponseWriterWrapper is an optional interface that extensions can implement
+// to wrap the response writer for capturing/modifying responses
+type ResponseWriterWrapper interface {
+	WrapResponseWriter(w http.ResponseWriter, r *http.Request) http.ResponseWriter
+}
+
+// ResponseFinalizer is an optional interface for response writers that need
+// to perform finalization after the response is written (e.g., caching)
+type ResponseFinalizer interface {
+	Finalize()
+}