feat: add Camera node type + flag RTSP/camera ports during scan

- New 'camera' node type with Camera icon (frontend + types)
- Scanner fingerprint: camera ports (554, 8554, 37777, 34567, 2020) now suggest 'camera' instead of 'iot'
- service_signatures.json: all camera/NVR entries updated to suggested_node_type=camera
- 'camera' added to priority list in suggest_node_type (above iot)

frontend/src/components/canvas/nodes/index.tsx

@@ -1,7 +1,7 @@
 import { type NodeProps, type Node } from '@xyflow/react'
 import {
   Globe, Router, Network, Server, Layers, Box, Container,
-  HardDrive, Cpu, Wifi, Circle,
+  HardDrive, Cpu, Wifi, Circle, Camera,
 } from 'lucide-react'
 import { BaseNode } from './BaseNode'
 import type { NodeData } from '@/types'
@@ -18,4 +18,5 @@ export const LxcNode     = (props: N) => <BaseNode {...props} icon={Container} /
 export const NasNode     = (props: N) => <BaseNode {...props} icon={HardDrive} />
 export const IotNode     = (props: N) => <BaseNode {...props} icon={Cpu} />
 export const ApNode      = (props: N) => <BaseNode {...props} icon={Wifi} />
+export const CameraNode  = (props: N) => <BaseNode {...props} icon={Camera} />
 export const GenericNode = (props: N) => <BaseNode {...props} icon={Circle} />