feat: build pipeline — .ts → .esm.js + .yaml + .d.ts 三件套

- add command auto-detects .ts vs .esm.js input
- .ts: Bun.build → bundle + descriptor extraction + JSON Schema → .d.ts
- .esm.js: requires .yaml alongside, .d.ts optional
- JSON Schema → TypeScript type converter
- hello-world example workflow
- 63 tests pass, biome clean

Closes #7
小橘 <xiaoju@shazhou.work>

packages/cli-workflow/src/bundle-store.ts

@@ -12,9 +12,7 @@ async function pathExists(path: string): Promise<boolean> {
   }
 }
 
-export type BundleFileSource =
-  | { kind: "text"; text: string }
-  | { kind: "path"; path: string };
+export type BundleFileSource = { kind: "text"; text: string } | { kind: "path"; path: string };
 
 export type WorkflowBundleStoreInput = {
   esmJs: BundleFileSource;