feat: add TypeScript installation wizard with @clack/prompts TUI

Replace bash mosaic-init with a modern 9-stage wizard:
- SOUL.md identity, USER.md profile, TOOLS.md configuration
- Runtime detection (Claude, Codex, OpenCode) + MCP setup
- Skills catalog with categorized selection
- Quick Start and Advanced modes
- HeadlessPrompter for --non-interactive and CI usage
- ConfigService abstraction layer for future DB migration
- Bundled as single dist/mosaic-wizard.mjs via tsdown
- mosaic init now prefers wizard when Node.js is available
- 30 tests covering stages, templates, and integration

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

tsdown.config.ts

@@ -0,0 +1,13 @@
+import { defineConfig } from 'tsdown';
+
+export default defineConfig({
+  entry: { 'mosaic-wizard': 'src/index.ts' },
+  format: 'esm',
+  outDir: 'dist',
+  clean: true,
+  noExternal: [/.*/],
+  inlineOnly: false,
+  banner: { js: '#!/usr/bin/env node' },
+  target: 'node18',
+  minify: false,
+});