Update dev.ps1 to load .env variables, switch to npm run build, and integrate act for workflow testing

Author: andrey-helldar

dev.ps1

@@ -2,4 +2,19 @@ $env:GITHUB_RUN_ID = 123
 $env:GITHUB_EVENT_NAME = "push"
 $env:GITHUB_EVENT_PATH = "TheDragonCode/preview-updater"
 
-npm run dev
+$envFile = ".env"
+
+Get-Content $envFile |
+        ForEach-Object {
+            if ($_ -match '^(?<key>[^=]+)=(?<val>.*)$')
+            {
+                $key = $Matches['key'].Trim()
+                $val = $Matches['val'].Trim()
+
+                $env: $key = $val
+            }
+        }
+
+npm run build
+
+act push -W '.github/workflows/preview.yml'