Refactor caching functions and simplify response serialization

- Updated the `downloadThroughCache` function to remove the upstream URL parameter, streamlining the caching process.
- Modified the `serializeRawResponse` function to eliminate unnecessary parameters, enhancing clarity and usability.
- Adjusted integration tests to align with the new function signatures, ensuring consistent testing of caching behavior.

steamcache/integration_test.go

@@ -52,7 +52,7 @@ func testSteamURL(t *testing.T, urlPath string) {
 	directResp, directBody := downloadDirectly(t, steamURL)
 
 	// Test download through SteamCache
-	cacheResp, cacheBody := downloadThroughCache(t, sc, steamURL, urlPath)
+	cacheResp, cacheBody := downloadThroughCache(t, sc, urlPath)
 
 	// Compare responses
 	compareResponses(t, directResp, directBody, cacheResp, cacheBody, urlPath)
@@ -83,7 +83,7 @@ func downloadDirectly(t *testing.T, url string) (*http.Response, []byte) {
 	return resp, body
 }
 
-func downloadThroughCache(t *testing.T, sc *SteamCache, upstreamURL, urlPath string) (*http.Response, []byte) {
+func downloadThroughCache(t *testing.T, sc *SteamCache, urlPath string) (*http.Response, []byte) {
 	// Create a test server for SteamCache
 	cacheServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		// For real Steam URLs, we need to set the upstream to the Steam hostname
@@ -235,7 +235,7 @@ func TestCacheFileFormat(t *testing.T) {
 	rawResponse := sc.reconstructRawResponse(resp, bodyData)
 
 	// Serialize to cache format
-	cacheData, err := serializeRawResponse("/test/format", rawResponse, contentHash, "sha256")
+	cacheData, err := serializeRawResponse(rawResponse)
 	if err != nil {
 		t.Fatalf("Failed to serialize cache file: %v", err)
 	}