feat: add PC monitoring tab with Windows agent

- New /api/pc endpoints (heartbeat, list, delete)
- Dashboard tabs: Серверы / ПК with auto-refresh
- PowerShell agent: CPU, RAM, Disk, Network, GPU, Top processes
- One-command Windows installer with Scheduled Task
- PC setup instructions modal

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

windows/README_PC.md

@@ -0,0 +1,50 @@
+# VPS Monitor — Windows PC Agent
+
+## Quick Install (one command)
+
+Run in PowerShell as Administrator:
+
+```powershell
+irm https://77.239.126.123.nip.io/static/downloads/install_agent.ps1 | iex -ServerUrl "http://77.239.126.123:7272" -AgentName "MyPC"
+```
+
+Or download and run:
+```powershell
+Invoke-WebRequest -Uri "http://77.239.126.123:7272/static/downloads/install_agent.ps1" -OutFile install_agent.ps1
+powershell -ExecutionPolicy Bypass -File install_agent.ps1 -ServerUrl "http://77.239.126.123:7272" -AgentName "Office-PC"
+```
+
+## What it monitors
+
+- CPU usage (%)
+- RAM usage (total, used, %)
+- Disk usage (all drives)
+- Network adapters (speed, traffic)
+- GPU info
+- Uptime
+- Top 5 processes by CPU
+
+## Files
+
+| File | Purpose |
+|------|---------|
+| `install_agent.ps1` | Installer (creates task, config) |
+| `vps_monitor_agent.ps1` | Agent (collects & sends metrics) |
+| `C:\VPS-Monitor\agent_config.json` | Config (server URL, name) |
+
+## Management
+
+```powershell
+# Check status
+Get-ScheduledTask 'VPS-Monitor-Agent'
+
+# Stop
+Stop-ScheduledTask 'VPS-Monitor-Agent'
+
+# Start
+Start-ScheduledTask 'VPS-Monitor-Agent'
+
+# Uninstall
+Unregister-ScheduledTask 'VPS-Monitor-Agent' -Confirm:$false
+Remove-Item -Recurse C:\VPS-Monitor
+```