Enhance SteamCache configuration and HTTP client settings

- Added upstream server configuration to launch.json for improved connectivity.
- Increased HTTP client timeout from 60s to 120s for better handling of slow responses.
- Updated server timeouts in steamcache.go: increased ReadTimeout to 30s and WriteTimeout to 60s.
- Introduced ReadHeaderTimeout to mitigate header attacks and set MaxHeaderBytes to 1MB.
- Improved error logging in the Run method to include HTTP status codes for better debugging.
- Adjusted ServeHTTP method to handle root path and metrics endpoint correctly.

.vscode/launch.json

@@ -23,6 +23,8 @@
                 "lru",
                 "--log-level",
                 "debug",
+                "--upstream",
+                "http://192.168.2.5:80",
             ],
         },
         {
@@ -40,6 +42,8 @@
                 "hybrid",
                 "--log-level",
                 "debug",
+                "--upstream",
+                "http://192.168.2.5:80",
             ],
         },
         {
@@ -55,6 +59,8 @@
                 "lfu",
                 "--log-level",
                 "debug",
+                "--upstream",
+                "http://192.168.2.5:80",
             ],
         }
     ]