fix: second-wave bug fixes, security hardening, visual polish, UX improvements

Bug fixes:
- SRV-B1 through B5: server config, router, server_info, syscheck corrections
- BA-03 through BA-06: builder path and universal build cleanup (BLD-D1 through D3)
- Frontend WS race condition and useVisibleInterval hook fixed
- Drive-root path bug in PathForge resolved
- Upload error handling improved

Security:
- PathForge path traversal guard added
- Script injection escaping applied throughout

Visual (DV-01 through DV-15):
- Cyan design tokens and page headers standardised
- Dead CSS removed from Pages.css, PathTracerPage.css, wealth-deck.css
- SacredPageHeader deleted (replaced inline); sidebar version display fixed

UX:
- Emberwake request storm fixed (EmberwakePage.tsx)
- Help blurbs UH-01, UH-02, UH-06 added
- HelpTips wired into Crucible, Fleet (FleetGroupsStrip, FleetToolbar), Settings

Build:
- vite.config.ts: webroot auto-sync on build
- build_universal.go: universal build artifact cleanup
- PROBLEMS.md tracking updated

agent/client/syscheck.go

@@ -57,7 +57,7 @@ func CollectFullSysCheck(cfg config.RuntimeConfig, agentID string) *FullSysCheck
 	arp := deploy.ArpNeighborIPs()
 	r.Neighbors.ArpHosts = arp
 	r.Neighbors.ArpCount = len(arp)
-	r.Neighbors.SubnetScan = deploy.ScanLocalSubnet(56)
+	r.Neighbors.SubnetScan = deploy.ScanLocalSubnet(20)
 
 	collectSysCheckPlatform(r)