feat(controller): intial build functions setup in go and service building

controller/builds.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+)
+
+// ensureBuildDir creates dir if missing
+func ensureBuildDir(dir string) (string, error) {
+    if _, err := os.Stat(dir); os.IsNotExist(err) {
+        if err := os.MkdirAll(dir, 0755); err != nil {
+            return "", err
+        }
+    }
+    return filepath.Clean(dir), nil
+}
+
+func getBuildDir() (string, error) {
+    if os.Getenv("RUNNING_IN_DOCKER") == "true" {
+        // In Docker: workdir is usually /app/controller, so .. points to /app (repo root)
+        return ensureBuildDir(filepath.Join("..", "builds"))
+    }
+
+    // Local dev: still want builds in repo root relative to controller/
+    return ensureBuildDir(filepath.Join("..", "builds"))
+}