feat(prdy): migrate @mosaic/prdy from v0 to v1

Port full PRD wizard implementation: types, YAML persistence (js-yaml),
built-in templates (software/feature/spike), @clack/prompts interactive
wizard, and Commander.js CLI (init/list/show). Adapted for v1 conventions:
ESM .js imports, NodeNext resolution, noUncheckedIndexedAccess-safe lookups,
and consistent-type-imports lint rule.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/prdy/src/index.ts

@@ -1 +1,12 @@
-export const VERSION = '0.0.0';
+export { createPrd, loadPrd, savePrd, listPrds } from './prd.js';
+export { runPrdWizard } from './wizard.js';
+export { buildPrdyCli, runPrdyCli } from './cli.js';
+export { BUILTIN_PRD_TEMPLATES, resolveTemplate } from './templates.js';
+export type {
+  PrdStatus,
+  PrdTemplate,
+  PrdTemplateSection,
+  PrdSection,
+  PrdDocument,
+  CreatePrdOptions,
+} from './types.js';