Schedule retry on startup peer-init failure

When initiate_peer_connections() runs at boot, address resolution can
fail for an entire peer (no operational transport for the configured
transport types, all addresses unreachable, NAT rebind invalidated cached
endpoints, etc.). Before this change the failure was logged and silently
forgotten — the peer entry stayed in a dead state forever, accepting
incoming pings but unable to answer them, until the daemon was manually
restarted.

The retry plumbing (schedule_retry / process_pending_retries with
exponential backoff) already exists and is wired into the post-handshake
failure paths (BootstrapEvent::Failed, MMP dead-link timeout, handshake
timeout). The startup loop just wasn't calling it. Mirror the
BootstrapEvent::Failed path: on a startup peer-init error, parse the
peer's npub and call schedule_retry so the peer recovers without
operator intervention.

Includes a regression test that asserts retry_pending is populated when
initiate_peer_connections() fails for a peer with no operational
transport.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/node/tests/unit.rs

@@ -952,6 +952,38 @@ fn test_promote_clears_retry_pending() {
     );
 }
 
+/// Initial peer-init failure at startup must enqueue a retry. Otherwise a peer
+/// whose addresses cannot be dialed at boot (no operational transport for the
+/// configured transport types, all addresses unreachable, NAT rebind, etc.)
+/// stays dead forever — pings arrive but cannot be answered until the daemon
+/// is manually restarted.
+#[tokio::test]
+async fn test_initiate_peer_connections_schedules_retry_on_no_transport() {
+    let peer_identity = Identity::generate();
+    let peer_npub = peer_identity.npub();
+    let peer_node_addr = *PeerIdentity::from_npub(&peer_npub).unwrap().node_addr();
+
+    let mut config = Config::new();
+    // udp address but no UDP transport registered on the node — every dial
+    // attempt resolves to NodeError::NoTransportForType.
+    config.peers.push(crate::config::PeerConfig::new(
+        peer_npub,
+        "udp",
+        "10.0.0.2:2121",
+    ));
+
+    let mut node = Node::new(config).unwrap();
+    assert!(node.retry_pending.is_empty());
+
+    node.initiate_peer_connections().await;
+
+    assert!(
+        node.retry_pending.contains_key(&peer_node_addr),
+        "startup peer-init failure must enqueue a retry so the peer can recover \
+         without a daemon restart"
+    );
+}
+
 // ============================================================================
 // transport_mtu() — ISSUE-2026-0011 regression coverage
 // ============================================================================