feat: add use cases marketing product with AI-generated content

Transform qualifying scenarios into marketing-ready use cases with:
- AI-generated titles, descriptions, ROI estimates, business value
- Persona/industry/category taxonomy for targeting
- Browseable feed with filtering and ranking
- SEO-optimized case study pages
- Daily cron job for generation and ranking

Database:
- Add Persona, Industry, Category lookup tables
- Add UseCase model with marketing content fields
- Add junction tables for personas/industries/categories
- Add SocialProof model for cached metrics

API:
- GET /api/use-cases - Global directory with filtering
- GET /api/use-cases/[id] - Individual use case details
- GET /api/public/users/[username]/collections/[slug]/use-cases
- POST /api/cron/use-cases - Nightly generation job

Frontend:
- /use-cases - Global feed with persona dropdown
- /use-cases/[slug] - SEO case study page
- /[username]/collections/[slug]/use-cases - Collection feed
- UseCasesFeed component - Sortable table component
- UseCaseCaseStudy component - Full case study layout

sync-hello.ts

@@ -36,9 +36,9 @@ async function syncHello() {
         npmVersion: pkg.version,
         npmPublishedAt: new Date(pkg.time[pkg.version]),
         npmDownloadsLastMonth: 0,
-        category: validation.packageData!.category,
-        env: validation.packageData!.env || null,
-        frameworks: validation.packageData!.frameworks || [],
+        category: validation.packageData?.category,
+        env: validation.packageData?.env || null,
+        frameworks: validation.packageData?.frameworks || [],
         tier: validation.tier!,
         discoveryMethod: 'manual',
         isOfficial: pkg.name.startsWith('@tpmjs/'),
@@ -46,9 +46,9 @@ async function syncHello() {
       update: {
         npmVersion: pkg.version,
         npmPublishedAt: new Date(pkg.time[pkg.version]),
-        category: validation.packageData!.category,
-        env: validation.packageData!.env || null,
-        frameworks: validation.packageData!.frameworks || [],
+        category: validation.packageData?.category,
+        env: validation.packageData?.env || null,
+        frameworks: validation.packageData?.frameworks || [],
         tier: validation.tier!,
       },
     });