feat(wave3): add @mosaic/prdy — TypeScript PRD wizard

- PRD CRUD: createPrd, loadPrd, savePrd, listPrds
- Interactive wizard using @clack/prompts
- Built-in templates: software, feature, spike
- CLI: prdy init | list | show
- Depends on @mosaic/types workspace:*

packages/prdy/tests/templates.test.ts

@@ -0,0 +1,22 @@
+import { describe, expect, it } from 'vitest';
+
+import { BUILTIN_PRD_TEMPLATES } from '../src/templates.js';
+
+describe('built-in PRD templates', () => {
+  it('includes software, feature, and spike templates with required fields', () => {
+    expect(BUILTIN_PRD_TEMPLATES.software).toBeDefined();
+    expect(BUILTIN_PRD_TEMPLATES.feature).toBeDefined();
+    expect(BUILTIN_PRD_TEMPLATES.spike).toBeDefined();
+
+    for (const template of Object.values(BUILTIN_PRD_TEMPLATES)) {
+      expect(template.sections.length).toBeGreaterThan(0);
+      expect(template.fields.length).toBeGreaterThan(0);
+
+      for (const section of template.sections) {
+        expect(section.id.length).toBeGreaterThan(0);
+        expect(section.title.length).toBeGreaterThan(0);
+        expect(section.fields.length).toBeGreaterThan(0);
+      }
+    }
+  });
+});