🔧 chore: enforce monorepo best practices with automated validation

Fix critical issues and add validation to prevent future violations:

**Fixes:**
- Remove turbo recursion in 5 app packages (infinite loop risk)
- Add "private": true to 11 packages (prevent accidental publishing)
- Rename @mana-core/nestjs-integration → @manacore/nestjs-integration
- Remove prepublishOnly scripts from 3 private packages

**New:**
- Add scripts/validate-monorepo.mjs with 4 critical checks
- Add validate:monorepo command to package.json
- Integrate validation into CI pipeline (.github/workflows/ci.yml)
- Document validation in CLAUDE.md

All 80 package.json files now pass validation ✅

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.github/workflows/ci.yml

@@ -51,6 +51,9 @@ jobs:
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
 
+      - name: Validate monorepo best practices
+        run: pnpm run validate:monorepo
+
       - name: Type check
         run: pnpm run type-check