feat(companion): npub-first pairing — node self-anchor + guaranteed public anchor in the QR

The pairing QR was effectively IP-first: the phone dialed the scanned LAN
host and went dark when the LAN renumbered or it left home. FIPS peers on
npubs; IPs are only dial hints. fanchors now leads with the paired node
ITSELF (fnpub @ current host, npub-keyed so LAN contact is direct p2p over
FIPS and survives DHCP), and fips.pair-info always includes the Archipelago
vps2 public anchor (pairing hint only — the node's own anchor file is not
modified) so the phone can rendezvous through the public mesh when away.
Contract doc updated with the REQUIRED app-side changes (built on the Mac).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

neode-ui/src/components/CompanionIntroOverlay.vue

@@ -348,9 +348,19 @@ async function buildPairingUrl(): Promise<string> {
       if (info.udp_port) params.set('fudp', String(info.udp_port))
       if (info.tcp_port) params.set('ftcp', String(info.tcp_port))
       // Rendezvous anchors (compact: npub@addr/transport, comma-joined).
-      // Cap keeps the QR at a camera-friendly density; the node lists its
-      // most reachable anchors first.
-      const anchors = (info.anchors || []).slice(0, 4)
+      // FIRST entry is the paired node ITSELF: the phone peers with it by
+      // npub (the fhost addr is only a dial hint), so LAN contact is direct
+      // p2p over FIPS and survives DHCP renumbering; the node's public
+      // anchors follow for reaching it away from home. Cap keeps the QR at a
+      // camera-friendly density; the node lists its most reachable anchors
+      // first.
+      const selfAnchor = info.tcp_port
+        ? [{ npub: info.npub, addr: `${params.get('fhost')}:${info.tcp_port}`, transport: 'tcp' }]
+        : []
+      const anchors = [
+        ...selfAnchor,
+        ...(info.anchors || []).filter((a) => a.npub !== info.npub),
+      ].slice(0, 4)
       if (anchors.length) {
         params.set(
           'fanchors',