feat: web console with real management operations

Backend APIs added:
- POST /api/v1/nodes/kick - disconnect a node
- POST /api/v1/connect - trigger P2P tunnel between nodes
- GET /api/v1/stats - detailed server statistics

Frontend features:
- Dashboard: real stats from /api/v1/stats (cone/symm/relay counts)
- Node management: table view, kick node, configure tunnels
- SDWAN: enable/disable, CIDR config, IP allocation, online status
- P2P Connect: create tunnel between two nodes from UI
- Event log: tracks all operations

internal/server/server.go

@@ -17,26 +17,26 @@ import (
 
 // NodeInfo represents a connected client node.
 type NodeInfo struct {
-	Name           string
-	Token          uint64
-	User           string
-	Version        string
-	NATType        protocol.NATType
-	PublicIP       string
-	PublicPort     int
-	LanIP          string
-	OS             string
-	Mac            string
-	ShareBandwidth int
-	RelayEnabled   bool
-	SuperRelay     bool
-	HasIPv4        int
-	IPv6           string
-	LoginTime      time.Time
-	LastHeartbeat  time.Time
-	Conn           *signal.Conn
-	Apps           []protocol.AppConfig
-	mu             sync.RWMutex
+	Name           string              `json:"name"`
+	Token          uint64              `json:"-"`
+	User           string              `json:"user"`
+	Version        string              `json:"version"`
+	NATType        protocol.NATType    `json:"natType"`
+	PublicIP       string              `json:"publicIP"`
+	PublicPort     int                 `json:"publicPort"`
+	LanIP          string              `json:"lanIP"`
+	OS             string              `json:"os"`
+	Mac            string              `json:"mac"`
+	ShareBandwidth int                 `json:"shareBandwidth"`
+	RelayEnabled   bool                `json:"relayEnabled"`
+	SuperRelay     bool                `json:"superRelay"`
+	HasIPv4        int                 `json:"hasIPv4"`
+	IPv6           string              `json:"ipv6"`
+	LoginTime      time.Time           `json:"loginTime"`
+	LastHeartbeat  time.Time           `json:"lastHeartbeat"`
+	Conn           *signal.Conn        `json:"-"`
+	Apps           []protocol.AppConfig `json:"apps"`
+	mu             sync.RWMutex        `json:"-"`
 }
 
 // IsOnline checks if node has sent heartbeat recently.