Add GET /api/v1/probe endpoint for device inspection

Fast (~1-3s) endpoint that gathers network info about a device
before full stream discovery. Runs ping first, then parallel probes.

Features:
- Ping with ICMP + TCP fallback (works without root)
- Reverse DNS hostname lookup
- ARP table MAC address + OUI vendor identification (2403 entries, 51 camera vendors)
- mDNS HomeKit detection (camera/doorbell, paired status)
- Extensible Prober interface for adding new probe types
- 3-second overall timeout, parallel execution

Response includes "type" field:
- "unreachable" - device not responding
- "standard" - normal IP camera (RTSP/HTTP/ONVIF flow)
- "homekit" - Apple HomeKit camera (PIN pairing flow)

internal/config/config.go

@@ -33,6 +33,7 @@ type DatabaseConfig struct {
 	BrandsPath     string
 	PatternsPath   string
 	ParametersPath string
+	OUIPath        string
 	CacheEnabled   bool
 	CacheTTL       time.Duration
 }
@@ -80,6 +81,7 @@ func Load() *Config {
 			BrandsPath:     filepath.Join(dataPath, "brands"),
 			PatternsPath:   filepath.Join(dataPath, "popular_stream_patterns.json"),
 			ParametersPath: filepath.Join(dataPath, "query_parameters.json"),
+			OUIPath:        filepath.Join(dataPath, "camera_oui.json"),
 			CacheEnabled:   true,
 			CacheTTL:       5 * time.Minute,
 		},