docs(rfc-001): add execution model — Role, Moderator, Agent types

Ported from nerve's workflow types. Covers ThreadContext, StartStep,
RoleStep, Moderator (pure router), Role (async actor), AgentFn (LLM adapter),
WorkflowDefinition, and execution flow.

小橘 <xiaoju@shazhou.work>

packages/workflow/tsconfig.json

@@ -0,0 +1,20 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "lib": ["ES2022"],
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "strict": true,
+    "exactOptionalPropertyTypes": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "declaration": true,
+    "declarationMap": true,
+    "sourceMap": true,
+    "composite": true,
+    "outDir": "dist",
+    "rootDir": "src"
+  },
+  "include": ["src/**/*.ts", "xxhashjs.d.ts"]
+}