chore: enforce folder module discipline in @uncaged/workflow

Each folder now has:
- types.ts for all type definitions
- index.ts with pure re-exports only
- Cross-folder imports go through index.ts

Closes #106

packages/workflow/src/bundle/extract-bundle-exports.ts

@@ -1,20 +1,10 @@
 import type { WorkflowFn } from "../types.js";
-import { err, ok, type Result } from "../util/result.js";
+import { err, ok, type Result } from "../util/index.js";
 import { importWorkflowBundleModule } from "./bundle-import-env.js";
 import { ensureUncagedWorkflowSymlink } from "./ensure-uncaged-workflow-symlink.js";
-import type { WorkflowDescriptor } from "./workflow-descriptor.js";
+import type { ExtractBundleExportsOptions, ExtractedBundleExports } from "./types.js";
 import { validateWorkflowDescriptor } from "./workflow-descriptor.js";
 
-export type ExtractedBundleExports = {
-  run: WorkflowFn;
-  descriptor: WorkflowDescriptor;
-};
-
-export type ExtractBundleExportsOptions = {
-  /** When set, ensures `node_modules/@uncaged/workflow` exists under this root before import. */
-  storageRoot: string | null;
-};
-
 /** Load a workflow `.esm.js` bundle and read its named exports (`run`, `descriptor`). */
 export async function extractBundleExports(
   bundlePath: string,