Add waitlist schema for marketing (FRE-635)

- Created waitlist_signups and waitlist_events tables
- Supports email, name, source tracking, and status management
- Enables VIP supporter list for Product Hunt launch
- Migration 0002_chemical_shocker.sql generated
- Fixed brand color in product-hunt-assets-brief.md (#518ac8)

src/lib/analytics/kpi-service.ts

@@ -42,7 +42,7 @@ export async function recordKPI(
     metadata: metadata ? JSON.stringify(metadata) : null,
   };
   const result = await db.insert(kpiSnapshots).values(snapshot).returning();
-  return result[0];
+  return result[0]!;
 }
 
 export async function getLatestKPI(