feat: 多主机纳管、用户认证、noVNC控制台、深色主题

主要功能:
- 多主机管理: 支持TCP/SSH方式纳管远程KVM主机
- 用户认证: JWT token认证, 默认admin/admin123
- noVNC控制台: 前端集成noVNC, WebSocket代理VNC连接
- 深色主题: 全局Element Plus深色主题覆盖
- 虚拟机操作: 克隆、迁移、XML编辑、快照管理
- 资源监控: CPU/内存/磁盘IO/网络流量实时监控

Bug修复:
- libvirt getInfo()内存单位修正(MiB非KiB)
- 远程主机VNC 0.0.0.0监听地址连接策略修复
- Dashboard定时器内存泄漏修复
- bcrypt版本兼容性修复

backend/app/routers/network.py

@@ -1,10 +1,10 @@
 """网络管理路由"""
-from fastapi import APIRouter, HTTPException
+from fastapi import APIRouter, HTTPException, Query
 from pydantic import BaseModel, Field
 from typing import Optional, List
 from lxml import etree
 
-from app.libvirt_conn import libvirt_conn
+from app.libvirt_conn import conn_pool
 import libvirt
 
 router = APIRouter()
@@ -20,15 +20,14 @@ class NetworkCreate(BaseModel):
 
 
 @router.get("/list")
-async def list_networks():
+async def list_networks(host_id: str = Query("local")):
     """列出所有网络"""
-    conn = libvirt_conn.conn
+    conn = conn_pool.get_conn(host_id)
     networks = conn.listAllNetworks(0)
     result = []
     for net in networks:
         xml = etree.fromstring(net.XMLDesc(0).encode())
 
-        # 解析网络信息
         forward = xml.find("forward")
         mode = forward.get("mode", "isolated") if forward is not None else "isolated"
 
@@ -39,18 +38,13 @@ async def list_networks():
         bridge = xml.find("bridge")
         bridge_name = bridge.get("name", "") if bridge is not None else ""
 
-        # DHCP范围
         dhcp_range = None
         dhcp = xml.find(".//dhcp")
         if dhcp is not None:
             r = dhcp.find("range")
             if r is not None:
-                dhcp_range = {
-                    "start": r.get("start", ""),
-                    "end": r.get("end", ""),
-                }
+                dhcp_range = {"start": r.get("start", ""), "end": r.get("end", "")}
 
-        # 活跃租约
         leases = []
         try:
             for lease in net.DHCPLeases():
@@ -79,9 +73,9 @@ async def list_networks():
 
 
 @router.get("/detail/{name}")
-async def get_network(name: str):
+async def get_network(name: str, host_id: str = Query("local")):
     """获取网络详情"""
-    conn = libvirt_conn.conn
+    conn = conn_pool.get_conn(host_id)
     try:
         net = conn.networkLookupByName(name)
     except libvirt.libvirtError:
@@ -92,7 +86,7 @@ async def get_network(name: str):
 
 
 @router.post("/create")
-async def create_network(net: NetworkCreate):
+async def create_network(net: NetworkCreate, host_id: str = Query("local")):
     """创建网络"""
     if net.mode == "bridge" and not net.bridge:
         raise HTTPException(status_code=400, detail="桥接模式必须指定桥接网卡")
@@ -104,7 +98,6 @@ async def create_network(net: NetworkCreate):
   <bridge name='{net.bridge}'/>
 </network>"""
     else:
-        # NAT或隔离模式
         import ipaddress
         network = ipaddress.ip_network(net.subnet, strict=False)
         gateway = str(network.network_address + 1)
@@ -129,7 +122,7 @@ async def create_network(net: NetworkCreate):
   </ip>
 </network>"""
 
-    with libvirt_conn.get_rw() as rw_conn:
+    with conn_pool.get_rw(host_id) as rw_conn:
         try:
             n = rw_conn.networkDefineXML(xml)
             n.setAutostart(1)
@@ -140,9 +133,9 @@ async def create_network(net: NetworkCreate):
 
 
 @router.delete("/delete/{name}")
-async def delete_network(name: str):
+async def delete_network(name: str, host_id: str = Query("local")):
     """删除网络"""
-    with libvirt_conn.get_rw() as rw_conn:
+    with conn_pool.get_rw(host_id) as rw_conn:
         try:
             net = rw_conn.networkLookupByName(name)
         except libvirt.libvirtError:
@@ -155,9 +148,9 @@ async def delete_network(name: str):
 
 
 @router.post("/action/{name}")
-async def network_action(name: str, action: str):
+async def network_action(name: str, action: str, host_id: str = Query("local")):
     """网络操作: start/stop"""
-    with libvirt_conn.get_rw() as rw_conn:
+    with conn_pool.get_rw(host_id) as rw_conn:
         try:
             net = rw_conn.networkLookupByName(name)
         except libvirt.libvirtError: