fix: resolve network mode SSE and logging issues

- Fixes 404 errors on /sse and /message endpoints in network mode.
- Updates dev container and go.mod to use a compatible Go version.
- Restores and improves startup logging for all transport modes.

pkg/log/log.go

@@ -45,7 +45,7 @@ func Default() *zap.Logger {
 				MaxAge:     30,
 			}))
 
-			if flag.Mode == "http" || flag.Mode == "sse" {
+			if flag.Mode == "http" || flag.Mode == "sse" || flag.Mode == "network" {
 				wss = append(wss, zapcore.AddSync(os.Stdout))
 			}