UMCPHandler_RenameAsset Refactoring Notes

What Changed

Switched to plain-text output. The handler now overrides Handle(... FStringBuilderBase&) instead of the JSON version. The output is minimal: just the new path on success, or a clear error message on failure.
Removed UE_LOG calls. Two UE_LOG calls were removed. Errors are reported via the output device.
Removed the empty if (bSuccess) {} block. This was dead code.
Used MCPUtils::SplitAssetPath instead of hand-rolled path splitting with FindLastChar. This is more consistent and handles edge cases (like empty asset names) that the original code did not.
Added AllContent() to the MCPAssets query so it can find assets outside /Game/ if needed.
Trimmed unused includes. Removed includes for headers that were not needed (BlueprintEditorUtils, SavePackage, PackageName, AssetRegistryModule, FileHelpers, Engine/Blueprint.h).
Improved parameter descriptions with examples to help the LLM caller understand the expected format.

The handler is simple and focused — it does one thing well.
MCPAssets is used correctly: Exact() match, ENone() + ETwo() error conditions, with errors routed directly to the output device.
The logic for "just a name with no slash means rename in place" is preserved and useful.

No FormatName/Identifies usage. This handler doesn't look up objects by display name — it works with exact package paths, which is the correct thing for asset rename. FormatName/Identifies are not applicable here since we're dealing with package paths, not display names of nodes/pins/graphs.
No batch support. The handler renames one asset at a time. Batch renaming could be useful, but it's a less common operation than batch pin connections, so this may not be worth the added complexity.
Error detail from RenameAssets is lost. IAssetTools::RenameAssets returns a bool but doesn't provide a detailed reason for failure. The error message is necessarily generic. I'm not sure if there's a way to get more detail from Unreal's rename API.
No validation of NewAssetName. We don't check for illegal characters in the new name before calling RenameAssets. Unreal will reject bad names, but a more specific error message could be helpful.