feat: Refactor service management scripts to use a unified dev script

- Added package.json to manage development scripts.
- Updated restart-services.ps1 to call the new dev script for starting services.
- Refactored start-admin.ps1, start-backend.ps1, start-frontend.ps1, and start-mcp.ps1 to utilize the dev script for starting respective services.
- Enhanced stop-services.ps1 to improve process termination logic by matching command patterns.

start-admin.ps1

@@ -5,29 +5,7 @@ param(
 $ErrorActionPreference = "Stop"
 
 $repoRoot = Split-Path -Parent $MyInvocation.MyCommand.Path
-$adminDir = Join-Path $repoRoot "admin"
+$devScript = Join-Path $repoRoot "dev.ps1"
 
-if (-not (Test-Path $adminDir)) {
-  throw "Admin directory not found: $adminDir"
-}
-
-Push-Location $adminDir
-
-try {
-  if ($Install -or -not (Test-Path (Join-Path $adminDir "node_modules"))) {
-    Write-Host "[admin] Installing dependencies..." -ForegroundColor Cyan
-    npm install
-    if ($LASTEXITCODE -ne 0) {
-      throw "npm install failed"
-    }
-  }
-
-  Write-Host "[admin] Starting Vite admin workspace..." -ForegroundColor Green
-  npm run dev
-  if ($LASTEXITCODE -ne 0) {
-    throw "npm run dev failed"
-  }
-}
-finally {
-  Pop-Location
-}
+& $devScript -Only admin -Install:$Install
+exit $LASTEXITCODE