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>

src/stages/skills-select.ts

@@ -0,0 +1,84 @@
+import type { WizardPrompter } from '../prompter/interface.js';
+import type { WizardState } from '../types.js';
+import { loadSkillsCatalog } from '../skills/catalog.js';
+import { SKILL_CATEGORIES, categorizeSkill } from '../skills/categories.js';
+
+function truncate(str: string, max: number): string {
+  if (str.length <= max) return str;
+  return str.slice(0, max - 1) + '\u2026';
+}
+
+export async function skillsSelectStage(
+  p: WizardPrompter,
+  state: WizardState,
+): Promise<void> {
+  p.separator();
+
+  const spin = p.spinner();
+  spin.update('Loading skills catalog...');
+
+  const catalog = loadSkillsCatalog(state.mosaicHome);
+  spin.stop(`Found ${catalog.length} available skills`);
+
+  if (catalog.length === 0) {
+    p.warn(
+      "No skills found. Run 'mosaic sync' after installation to fetch skills.",
+    );
+    state.selectedSkills = [];
+    return;
+  }
+
+  if (state.mode === 'quick') {
+    const defaults = catalog
+      .filter((s) => s.recommended)
+      .map((s) => s.name);
+    state.selectedSkills = defaults;
+    p.note(
+      `Selected ${defaults.length} recommended skills.\n` +
+        `Run 'mosaic sync' later to browse the full catalog.`,
+      'Skills',
+    );
+    return;
+  }
+
+  // Advanced mode: categorized browsing
+  p.note(
+    'Skills give agents domain expertise for specific tasks.\n' +
+      'Browse by category and select the ones you want.\n' +
+      "You can always change this later with 'mosaic sync'.",
+    'Skills Selection',
+  );
+
+  // Build grouped options
+  const grouped: Record<
+    string,
+    { value: string; label: string; hint?: string; selected?: boolean }[]
+  > = {};
+
+  // Initialize all categories
+  for (const categoryName of Object.keys(SKILL_CATEGORIES)) {
+    grouped[categoryName] = [];
+  }
+
+  for (const skill of catalog) {
+    const category = categorizeSkill(skill.name, skill.description);
+    if (!grouped[category]) grouped[category] = [];
+    grouped[category].push({
+      value: skill.name,
+      label: skill.name,
+      hint: truncate(skill.description, 60),
+      selected: skill.recommended,
+    });
+  }
+
+  // Remove empty categories
+  for (const key of Object.keys(grouped)) {
+    if (grouped[key].length === 0) delete grouped[key];
+  }
+
+  state.selectedSkills = await p.groupMultiselect({
+    message: 'Select skills (space to toggle)',
+    options: grouped,
+    required: false,
+  });
+}