feat: add telemetry build provenance

Stamp official Docker builds with a low-cardinality provenance marker and report build_provenance/image_modified in anonymous telemetry. Local and fork builds default to custom, while official GitHub/GitLab release paths mark images as official.

scripts/docker-build-images.ps1

@@ -5,12 +5,18 @@ $imageNamespace = if ($env:IMAGE_NAMESPACE) { $env:IMAGE_NAMESPACE } else { "325
 $imageTag = if ($env:IMAGE_TAG) { $env:IMAGE_TAG } else { "local" }
 $imagePrefix = if ($env:IMAGE_PREFIX) { $env:IMAGE_PREFIX } else { "remnawave-minishop" }
 $dockerfile = if ($env:DOCKERFILE) { $env:DOCKERFILE } else { "deploy/docker/Dockerfile" }
+$buildProvenance = if ($env:REMNAWAVE_MINISHOP_BUILD_PROVENANCE) { $env:REMNAWAVE_MINISHOP_BUILD_PROVENANCE } else { "custom" }
 
 function Build-Image {
     param([string]$Target)
     $image = "$imageRegistry/$imageNamespace/$imagePrefix-$Target`:$imageTag"
     Write-Host "Building $image" -ForegroundColor Cyan
-    docker build -f $dockerfile --target $Target -t $image .
+    docker build `
+        -f $dockerfile `
+        --target $Target `
+        --build-arg "REMNAWAVE_MINISHOP_BUILD_PROVENANCE=$buildProvenance" `
+        -t $image `
+        .
 }
 
 Build-Image backend