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>

test/nodeSpec.test.js

@@ -0,0 +1,70 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { validateGraph, NODE_KINDS } from "../src/nodeSpec.js";
+
+test("validateGraph allows missing bp_path (auto-detect mode)", () => {
+  const errs = validateGraph({ nodes: [] });
+  assert.deepEqual(errs, []);
+});
+
+test("validateGraph rejects bp_path not under /Game/ when provided", () => {
+  const errs = validateGraph({ bp_path: "/Engine/Foo", nodes: [] });
+  assert.ok(errs.some(e => e.includes("bp_path")));
+});
+
+test("validateGraph accepts empty-string bp_path as auto-detect", () => {
+  const errs = validateGraph({ bp_path: "", nodes: [] });
+  assert.deepEqual(errs, []);
+});
+
+test("validateGraph accepts a minimal valid graph", () => {
+  const errs = validateGraph({
+    bp_path: "/Game/Test/BP_Foo",
+    nodes: [{ id: "n1", kind: "branch" }],
+    edges: [],
+  });
+  assert.deepEqual(errs, []);
+});
+
+test("validateGraph catches duplicate ids", () => {
+  const errs = validateGraph({
+    bp_path: "/Game/X",
+    nodes: [
+      { id: "a", kind: "branch" },
+      { id: "a", kind: "sequence" },
+    ],
+  });
+  assert.ok(errs.some(e => e.includes("duplicate")));
+});
+
+test("validateGraph catches unknown kind", () => {
+  const errs = validateGraph({
+    bp_path: "/Game/X",
+    nodes: [{ id: "a", kind: "teleport_to_mars" }],
+  });
+  assert.ok(errs.some(e => e.includes("teleport_to_mars")));
+});
+
+test("validateGraph catches edge to unknown node", () => {
+  const errs = validateGraph({
+    bp_path: "/Game/X",
+    nodes: [{ id: "a", kind: "branch" }],
+    edges: [{ from: ["a", "Then"], to: ["ghost", "Exec"] }],
+  });
+  assert.ok(errs.some(e => e.includes("ghost")));
+});
+
+test("NODE_KINDS contains the documented set", () => {
+  for (const k of [
+    "call_function", "event", "custom_event", "component_event",
+    "variable_get", "variable_set", "self",
+    "branch", "sequence",
+    "switch_int", "switch_string", "switch_enum",
+    "macro", "cast",
+    "make_array", "make_struct", "break_struct", "set_fields_in_struct",
+    "spawn_actor", "format_text", "get_subsystem", "load_asset",
+    "bind_delegate", "unbind_delegate", "call_delegate", "assign_delegate",
+  ]) {
+    assert.ok(NODE_KINDS.has(k), `missing kind: ${k}`);
+  }
+});