feat(landing): add shared-landing-ui package and manadeck landing page

- Create @manacore/shared-landing-ui package with reusable components
  (FeatureSection, StepsSection, FAQSection, CTASection, Card atoms)
- Add complete landing page for manadeck app
- Refactor märchenzauber landing to use shared components
  (remove local CTA, FAQ, Features, HowItWorks sections)
- Add German localization for manacore and memoro landing pages
- Update workspace configuration and package dependencies

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

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

pnpm-workspace.yaml

@@ -4,6 +4,7 @@ packages:
   - 'manacore'
   - 'manadeck'
   - 'memoro'
+  - 'picture'
 
   # Sub-apps within projects
   - 'maerchenzauber/apps/*'
@@ -12,6 +13,8 @@ packages:
   - 'manadeck/apps/*'
   - 'manadeck/backend'
   - 'memoro/apps/*'
+  - 'picture/apps/*'
+  - 'picture/packages/*'
 
-  # Future shared packages
+  # Shared packages
   - 'packages/*'