Add tests for main package, manager, and various components

- Introduced unit tests for the main package to ensure compilation.
- Added tests for the manager, including validation of upload sessions and handling of Blender binary paths.
- Implemented tests for job token generation and validation, ensuring security and integrity.
- Created tests for configuration management and database schema to verify functionality.
- Added tests for logger and runner components to enhance overall test coverage and reliability.

internal/runner/workspace/workspace_test.go

@@ -0,0 +1,40 @@
+package workspace
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestSanitizeName_ReplacesUnsafeChars(t *testing.T) {
+	got := sanitizeName("runner / with\\bad:chars")
+	if strings.ContainsAny(got, " /\\:") {
+		t.Fatalf("sanitizeName did not sanitize input: %q", got)
+	}
+}
+
+func TestFindBlendFiles_IgnoresBlendSaveFiles(t *testing.T) {
+	dir := t.TempDir()
+	if err := os.WriteFile(filepath.Join(dir, "scene.blend"), []byte("x"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "scene.blend1"), []byte("x"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	files, err := FindBlendFiles(dir)
+	if err != nil {
+		t.Fatalf("FindBlendFiles failed: %v", err)
+	}
+	if len(files) != 1 || files[0] != "scene.blend" {
+		t.Fatalf("unexpected files: %#v", files)
+	}
+}
+
+func TestFindFirstBlendFile_ReturnsErrorWhenMissing(t *testing.T) {
+	_, err := FindFirstBlendFile(t.TempDir())
+	if err == nil {
+		t.Fatal("expected error when no blend file exists")
+	}
+}
+