[UI] Add justfile to build frontend (#2897)

* [UI] Add justfile to build frontend

* Fix linter

Author: peterschmidt85

.justfile

@@ -14,4 +14,4 @@ set allow-duplicate-recipes
 
 import "runner/.justfile"
 
-# TODO: Add frontend/justfile for managing frontend development tasks
+import "frontend/.justfile"

frontend/.justfile

@@ -0,0 +1,20 @@
+# Justfile for building frontend
+#
+# Run `just` to see all available commands
+
+default:
+    @just --list
+
+[private]
+install-frontend:
+    #!/usr/bin/env bash
+    set -e
+    cd {{source_directory()}}
+    npm install
+
+build-frontend:
+    #!/usr/bin/env bash
+    set -e
+    cd {{source_directory()}}
+    npm run build
+    cp -r build/ ../src/dstack/_internal/server/statics/