Refactor: Move multi-DLL search logic to Editor.Core #15

Move all "search in multiple DLLs" (engine assembly, user code assembly, etc) logic from the Studio UI (Gaya.Plugin.GameStudio) to Turian.Editor.Core so the Studio stays a UI shell with minimal non-UI code.

Currently, assembly scanning and type discovery across loaded DLLs is partially in Editor.Core (ComponentRegistry, NodeInspectorController) but some search-related logic remains in the Studio UI layer. Consolidating this in Core will make the Studio a thinner UI shell.

Tasks:

• Audit Gaya.Plugin.GameStudio for any remaining multi-assembly search logic (e.g. AssetBrowserPanel, ValueEditorRegistry)
• Move search services, providers, or query logic to Editor.Core under an appropriate namespace (e.g., Turian.Editor.Core.Search or extend existing Inspector/Build modules)
• Define clean interfaces in Core that Studio can consume without knowing about assembly loading details
• Ensure BuildManager.LoadedAssemblies and related assembly enumeration is fully abstracted in Core
• Update Studio to only bind to Core search results without performing its own DLL scanning
• Verify no UI dependencies leak into Core during the move

Acceptance Criteria:

• Turian.Editor.Core contains all logic for searching across multiple loaded DLLs (engine, user code, etc).
• Gaya.Plugin.GameStudio only handles UI binding and delegates all search queries to Core.
• No Guinevere, Gaya or other UI-specific dependencies exist in Editor.Core.
• Existing search functionality (component search, asset search, etc) continues to work unchanged.