fix routes not being saved when new nodes registers (#2444)

* add test to validate exitnode propagation

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

* save routes on register

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

* update changelog

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

* no nil

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

* add missing integration tests

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

---------

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

hscontrol/db/node.go

@@ -453,6 +453,10 @@ func RegisterNode(tx *gorm.DB, node types.Node, ipv4 *netip.Addr, ipv6 *netip.Ad
 		return nil, fmt.Errorf("failed register(save) node in the database: %w", err)
 	}
 
+	if _, err := SaveNodeRoutes(tx, &node); err != nil {
+		return nil, fmt.Errorf("failed to save node routes: %w", err)
+	}
+
 	log.Trace().
 		Caller().
 		Str("node", node.Hostname).