feat(config): add configurable packet channel buffer size

- Add PacketBufferSize field to api.Config struct
- Add DefaultPacketBuffer constant (1000 packets)
- Add JA4SENTINEL_PACKET_BUFFER_SIZE environment variable support
- Update mergeConfigs to handle PacketBufferSize override
- Update main.go to use configurable buffer size with fallback
- Update config.yml.example with packet_buffer_size option

Allows tuning for high-traffic environments by increasing buffer size
via config file or environment variable

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

cmd/ja4sentinel/main.go

@@ -84,8 +84,12 @@ func main() {
 		os.Exit(1)
 	}
 
-	// Create channel for raw packets
-	packetChan := make(chan api.RawPacket, 1000)
+	// Create channel for raw packets (configurable buffer size)
+	bufferSize := appConfig.Core.PacketBufferSize
+	if bufferSize <= 0 {
+		bufferSize = 1000 // Default fallback
+	}
+	packetChan := make(chan api.RawPacket, bufferSize)
 
 	// Start capture goroutine
 	captureErrChan := make(chan error, 1)