Unified, portable Unreal Engine MCP system plugin

Merge of the two project copies into one self-contained plugin (the superset:
variable_op + variables.py, full pcg_op runtime/declarative/preset ops, the
CreateWidgetFloatAnimation widget tool, and full Voxel graph authoring).

Made fully project- and machine-agnostic — no hardcoded paths:
- New src/projectPaths.js auto-detects the host .uproject (walk-up), project
  name, Editor build target, log file, and engine install (EngineAssociation
  via launcher manifest/registry, else installed-engine scan). All overridable
  via UE_* env vars.
- Rewired buildOrchestrator/insights/launcher/insightsExporter/server.js and the
  Python workers (cpp_scaffold, live_coding, apply_graph, console) off the old
  C:/Github/ihy, IHY*, E:/UE_Versions and UE_5.7 literals onto the resolver.
- Voxel made optional: Build.cs auto-detects the Voxel plugin (env
  UE_MCP_WITH_VOXEL override) and the C++ compiles to stubs under WITH_MCP_VOXEL,
  so the module builds in projects without Voxel; .uplugin marks Voxel optional.
- De-branded the agent-gateway and docs; scrubbed a leaked API key; excluded
  node_modules/Binaries/Intermediate/__pycache__/secrets from the repo.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

UEBlueprintMCP.uplugin

@@ -0,0 +1,36 @@
+{
+    "FileVersion": 3,
+    "Version": 1,
+    "VersionName": "0.1.0",
+    "FriendlyName": "Unreal Engine MCP System",
+    "Description": "Editor-only C++/Python helpers that expose the UE editor (Blueprint graphs, UMG, materials, Niagara, PCG, assets, build, Insights, ...) as MCP tools. Project- and machine-agnostic: all paths are auto-detected.",
+    "Category": "Editor",
+    "CreatedBy": "ExbyteLabs",
+    "CreatedByURL": "https://gitea.exbytestudios.com/ExbyteLabs/unreal-engine-mcp-system-plugin",
+    "DocsURL": "https://gitea.exbytestudios.com/ExbyteLabs/unreal-engine-mcp-system-plugin",
+    "MarketplaceURL": "",
+    "SupportURL": "https://gitea.exbytestudios.com/ExbyteLabs/unreal-engine-mcp-system-plugin",
+    "EnabledByDefault": true,
+    "CanContainContent": false,
+    "IsBetaVersion": true,
+    "IsExperimentalVersion": false,
+    "Installed": false,
+    "Modules": [
+        {
+            "Name": "UEBlueprintMCPEditor",
+            "Type": "Editor",
+            "LoadingPhase": "Default"
+        }
+    ],
+    "Plugins": [
+        {
+            "Name": "Voxel",
+            "Enabled": true,
+            "Optional": true
+        },
+        {
+            "Name": "Niagara",
+            "Enabled": true
+        }
+    ]
+}