refactor(workflow): migrate downstream packages to workflow-runtime (Phase 2+3)

- Verify createWorkflow in runtime has zero I/O imports
- Migrate agent-cursor, agent-hermes to pure workflow-runtime dependency
- Migrate agent-llm, util-agent, templates to dual dependency
  (runtime for types, engine for CAS/merkle/buildDescriptor)
- All 377 tests passing

Refs #121, relates #123 #124

packages/workflow-agent-cursor/__tests__/cursor-agent.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, test } from "bun:test";
-import type { ExtractContext, ExtractFn } from "@uncaged/workflow";
+import type { ExtractContext, ExtractFn } from "@uncaged/workflow-runtime";
 import type * as z from "zod/v4";
 import { createCursorAgent, validateCursorAgentConfig } from "../src/index.js";
 

packages/workflow-agent-cursor/package.json

@@ -8,7 +8,7 @@
     "test": "bun test"
   },
   "dependencies": {
-    "@uncaged/workflow": "workspace:*",
+    "@uncaged/workflow-runtime": "workspace:*",
     "@uncaged/workflow-util-agent": "workspace:*",
     "zod": "^4.0.0"
   }

packages/workflow-agent-cursor/src/index.ts

@@ -1,4 +1,4 @@
-import type { AgentFn, ExtractContext } from "@uncaged/workflow";
+import type { AgentFn, ExtractContext } from "@uncaged/workflow-runtime";
 import { buildAgentPrompt, type SpawnCliError, spawnCli } from "@uncaged/workflow-util-agent";
 import * as z from "zod/v4";
 

packages/workflow-agent-cursor/src/types.ts

@@ -1,4 +1,4 @@
-import type { ExtractFn } from "@uncaged/workflow";
+import type { ExtractFn } from "@uncaged/workflow-runtime";
 
 export type CursorAgentConfig = {
   model: string | null;

packages/workflow-agent-cursor/src/validate-config.ts

@@ -1,4 +1,4 @@
-import { err, ok, type Result } from "@uncaged/workflow";
+import { err, ok, type Result } from "@uncaged/workflow-runtime";
 
 import type { CursorAgentConfig } from "./types.js";