feat(docker): convert push script to PowerShell

scripts/docker_push.ps1

@@ -0,0 +1,53 @@
+# scripts/docker_push.ps1
+# Build and push Manual Slop image to Gitea container registry.
+
+$ErrorActionPreference = "Stop"
+
+$ProjectRoot = Split-Path -Parent $PSScriptRoot
+$CredsFile = Join-Path $ProjectRoot "credentials.toml"
+
+if (-not (Test-Path $CredsFile)) {
+    Write-Error "credentials.toml not found at $CredsFile"
+    exit 1
+}
+
+Write-Host "Reading credentials from credentials.toml..."
+
+$pyScript = @"
+import tomllib
+with open(r'$CredsFile', 'rb') as f:
+    creds = tomllib.load(f)
+g = creds.get('gitea', {})
+print(g.get('registry_url', '') + '|' + g.get('username', '') + '|' + g.get('token', ''))
+"@
+
+$credsJson = python -c $pyScript
+
+$parts = $credsJson -split '\|'
+$registryUrl = $parts[0].TrimEnd('/')
+$giteaUser = $parts[1]
+$giteaToken = $parts[2]
+
+if (-not $registryUrl -or -not $giteaUser -or -not $giteaToken) {
+    Write-Error "Gitea credentials incomplete in credentials.toml"
+    Write-Error "Required: registry_url, username, token"
+    exit 1
+}
+
+$registryHost = $registryUrl -replace 'https?://', ''
+$imageName = "manual_slop:latest"
+$fullTag = "$registryHost/$giteaUser/$imageName"
+
+Write-Host "Building Docker image..."
+docker build -t $imageName $ProjectRoot
+
+Write-Host "Tagging for Gitea registry: $fullTag"
+docker tag $imageName $fullTag
+
+Write-Host "Logging in to Gitea registry..."
+$giteaToken | docker login $registryHost -u $giteaUser --password-stdin
+
+Write-Host "Pushing to Gitea registry..."
+docker push $fullTag
+
+Write-Host "Done! Image available at: $fullTag"