feat: add system, uptime, network and processes widgets

Add four new server statistics widgets:
- SystemWidget: displays hostname, OS, and kernel information
- UptimeWidget: shows server total uptime with formatted display
- NetworkWidget: lists network interfaces with IP and status
- ProcessesWidget: displays top processes by CPU usage

Backend changes:
- Extended SSH metrics collection to gather network, uptime, process, and system data
- Added commands to parse /proc/uptime, ip addr, ps aux output

Frontend changes:
- Created 4 new widget components with consistent styling
- Updated widget type definitions and HostManagerEditor
- Unified all widget heights to 280px for consistent layout
- Added translations for all new widgets (EN/ZH)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/locales/en/translation.json

@@ -1169,7 +1169,18 @@
     "saveLayout": "Save Layout",
     "unsavedChanges": "Unsaved changes",
     "layoutSaved": "Layout saved successfully",
-    "failedToSaveLayout": "Failed to save layout"
+    "failedToSaveLayout": "Failed to save layout",
+    "systemInfo": "System Information",
+    "hostname": "Hostname",
+    "operatingSystem": "Operating System",
+    "kernel": "Kernel",
+    "totalUptime": "Total Uptime",
+    "seconds": "seconds",
+    "networkInterfaces": "Network Interfaces",
+    "noInterfacesFound": "No network interfaces found",
+    "totalProcesses": "Total Processes",
+    "running": "Running",
+    "noProcessesFound": "No processes found"
   },
   "auth": {
     "loginTitle": "Login to Termix",

src/locales/zh/translation.json

@@ -1149,7 +1149,18 @@
     "saveLayout": "保存布局",
     "unsavedChanges": "有未保存的更改",
     "layoutSaved": "布局保存成功",
-    "failedToSaveLayout": "保存布局失败"
+    "failedToSaveLayout": "保存布局失败",
+    "systemInfo": "系统信息",
+    "hostname": "主机名",
+    "operatingSystem": "操作系统",
+    "kernel": "内核",
+    "totalUptime": "总运行时间",
+    "seconds": "秒",
+    "networkInterfaces": "网络接口",
+    "noInterfacesFound": "未找到网络接口",
+    "totalProcesses": "总进程数",
+    "running": "运行中",
+    "noProcessesFound": "未找到进程"
   },
   "auth": {
     "loginTitle": "登录 Termix",