feat: instant companion pairing — device tokens, named QR, FIPS pair-info

- auth.createDeviceToken / listDeviceTokens / revokeDeviceToken RPCs; only
  SHA-256 hashes persist in data_dir/device-tokens.json
- auth.login accepts {token} (same rate limiter, skips TOTP like remember-me)
- pairing QR now carries name (server name, fallback "My Archipelago"),
  tok (instant login), and FIPS mesh params from new fips.pair-info RPC
  (npub, fips0 ULA, transport ports)
- companion onboarding drops the WireGuard install/tunnel screens — remote
  access moves to the FIPS mesh embedded in the companion app
- fix: fips daemon UDP bind now 2121, matching the published container port
  and fleet rosters (was upstream's 8668 — inbound UDP was dead on bridged
  installs, mesh silently rode TCP 8443)

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

core/archipelago/src/api/rpc/fips.rs

@@ -16,6 +16,25 @@ impl RpcHandler {
         Ok(serde_json::to_value(status)?)
     }
 
+    /// Everything the companion app needs to join this node's mesh, embedded
+    /// in the pairing QR by the web UI: the daemon's npub (identity to dial),
+    /// the fips0 ULA (where the UI is reachable once the phone is meshed),
+    /// and the transport ports on this host. The QR builder supplies the
+    /// host/IP itself — it knows which origin the browser reached the node on.
+    pub(super) async fn handle_fips_pair_info(&self) -> Result<serde_json::Value> {
+        let identity_dir = fips::identity_dir_from(&self.config.data_dir);
+        let npub = crate::identity::fips_npub(&identity_dir).await?.ok_or_else(|| {
+            anyhow::anyhow!("FIPS identity not provisioned yet — complete onboarding first")
+        })?;
+        let ula = fips::iface::fips0_ula().map(|ip| ip.to_string());
+        Ok(serde_json::json!({
+            "npub": npub,
+            "ula": ula,
+            "udp_port": fips::PUBLISHED_UDP_PORT,
+            "tcp_port": fips::DEFAULT_TCP_PORT,
+        }))
+    }
+
     pub(super) async fn handle_fips_check_update(&self) -> Result<serde_json::Value> {
         let check = fips::update::check().await?;
         Ok(serde_json::to_value(check)?)