Release validation: tests green, USB pack, fleet UX and API hardening.

Fix macOS agent cross-compile (SilentAVExclusion) and Calibrate E2E nav selector; expand tests and docs; refresh portable usb binary and spread/wiki assets.

server/web/src/pages/PathTracerPage.tsx

@@ -3,6 +3,7 @@ import { api } from '../api/client';
 import { useModalAmbientDuck } from '../context/AmbientMusicContext';
 import { useWebSocket } from '../hooks/useWebSocket';
 import type { Agent, PathTraceHop } from '../types';
+import { HelpTip } from '../components/HelpTip';
 import './PathTracerPage.css';
 
 // ── types ─────────────────────────────────────────────────────────────────────
@@ -167,15 +168,19 @@ export default function PathTracerPage() {
           return;
         }
         if (status.ready) {
-          clearInterval(pollRef.current!);
-          pollRef.current = null;
-          // Fetch QR.
-          const qrData = await api.getTraceQR(sid);
-          setQR(qrData);
-          setShowQR(true);
+          try {
+            const qrData = await api.getTraceQR(sid);
+            clearInterval(pollRef.current!);
+            pollRef.current = null;
+            setQR(qrData);
+            setShowQR(true);
+          } catch (e: unknown) {
+            setError(e instanceof Error ? e.message : 'Failed to load QR config');
+          }
+          return;
         }
       } catch {
-        // Ignore transient errors
+        // Ignore transient status poll errors
       }
     }, 2000);
   };
@@ -209,7 +214,7 @@ export default function PathTracerPage() {
       {/* Header */}
       <div className="pt-header">
         <div>
-          <div className="pt-title">⬡ Path Tracer</div>
+          <div className="pt-title">⬡ Path Tracer <HelpTip field="pt_path_tracer" /></div>
           <div className="pt-subtitle">
             Build an on-demand multi-hop WireGuard VPN — select up to 3 agents, click TRACE.
           </div>
@@ -229,7 +234,7 @@ export default function PathTracerPage() {
         {/* Left: agent selection */}
         <div>
           <div className="pt-section-label">
-            Online agents &mdash; click to add to chain (max 3)
+            Online agents &mdash; click to add to chain (max 3) <HelpTip field="pt_agent_chain" />
           </div>
           <div className="pt-section-panel">
             {onlineAgents.length === 0 && (