Refactor installation and runner scripts for enhanced usability and security

- Updated the installation script to clarify that production wrappers do not include fixed test secrets, improving user guidance for local testing.
- Modified the jiggablend-manager and jiggablend-runner scripts to remove fixed test configurations, emphasizing the use of local test credentials via `make init-test`.
- Enhanced error handling in the runner script to ensure that an API key is provided, improving security and user feedback.
- Added new flags and options for the runner, including sandboxing capabilities and GPU ray tracing control, enhancing flexibility for users.
- Improved README documentation to reflect changes in usage and configuration, ensuring users have clear instructions for setup and execution.

internal/manager/metadata_merge.go

@@ -0,0 +1,70 @@
+package api
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"jiggablend/pkg/types"
+)
+
+func uploadSessionMetadata(session *UploadSession) *types.BlendMetadata {
+	if session == nil || session.ResultMetadata == nil {
+		return nil
+	}
+
+	switch m := session.ResultMetadata.(type) {
+	case *types.BlendMetadata:
+		return m
+	case types.BlendMetadata:
+		meta := m
+		return &meta
+	default:
+		data, err := json.Marshal(session.ResultMetadata)
+		if err != nil {
+			return nil
+		}
+		var meta types.BlendMetadata
+		if err := json.Unmarshal(data, &meta); err != nil {
+			return nil
+		}
+		return &meta
+	}
+}
+
+// mergeBlendMetadataForJobCreate starts from upload analysis metadata when available,
+// then applies explicit job creation overrides from the request.
+func mergeBlendMetadataForJobCreate(uploadMeta *types.BlendMetadata, req *types.CreateJobRequest) (*types.BlendMetadata, error) {
+	if req.FrameStart == nil || req.FrameEnd == nil {
+		return nil, fmt.Errorf("frame_start and frame_end are required")
+	}
+
+	var metadata types.BlendMetadata
+	if uploadMeta != nil {
+		metadata = *uploadMeta
+	}
+
+	metadata.FrameStart = *req.FrameStart
+	metadata.FrameEnd = *req.FrameEnd
+
+	if req.RenderSettings != nil {
+		metadata.RenderSettings = *req.RenderSettings
+	}
+	if req.OutputFormat != nil {
+		metadata.RenderSettings.OutputFormat = *req.OutputFormat
+	}
+	if req.BlenderVersion != nil && *req.BlenderVersion != "" {
+		metadata.BlenderVersion = *req.BlenderVersion
+	}
+	if req.UnhideObjects != nil {
+		metadata.UnhideObjects = req.UnhideObjects
+	}
+	if req.EnableExecution != nil {
+		metadata.EnableExecution = req.EnableExecution
+	}
+
+	if metadata.BlenderVersion == "" {
+		return nil, fmt.Errorf("blender_version is required (from upload analysis or job request)")
+	}
+
+	return &metadata, nil
+}