feat: add multi-app support with app switcher, per-app branding, and filtered queries

Apps share the same backend, API keys, and publishing flow but each gets its own
branding (name, colors, icon, app URL), knowledge files (brand identity, product
info, platform guidelines), and campaigns. The pipeline dynamically writes
_knowledge/ files and copies app assets before each run.

- Add App model with slug, colors, appUrl, and knowledge markdown fields
- Add appId FK to Campaign, seed honeyDue as first app with existing knowledge
- App switcher dropdown in sidebar with icon previews
- Filter campaigns, stats, and assets by active app (cookie-based)
- De-hardcode lib/claude.ts: AppConfig interface, templated prompts, dynamic
  _knowledge/ and Remotion asset copying
- App management pages (list, create, edit) with icon upload and color pickers
- Asset library sort options (newest, oldest, name, platform, type)
- Asset cards show creation date
- Remotion HoneyDueAd accepts colors/appName props

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

prisma/schema.prisma

@@ -15,6 +15,23 @@ model User {
   createdAt DateTime @default(now())
 }
 
+model App {
+  id                 String     @id @default(cuid())
+  name               String
+  slug               String     @unique
+  description        String?
+  primaryColor       String     @default("#0079FF")
+  accentColor        String     @default("#FF9400")
+  darkBg             String     @default("#1a1a2e")
+  appUrl             String?
+  brandIdentity      String?
+  productInfo        String?
+  platformGuidelines String?
+  createdAt          DateTime   @default(now())
+  updatedAt          DateTime   @updatedAt
+  campaigns          Campaign[]
+}
+
 model Campaign {
   id             String          @id @default(cuid())
   name           String
@@ -23,6 +40,8 @@ model Campaign {
   platforms      String // JSON array: ["instagram","tiktok","nextdoor"]
   config         String? // JSON: full campaign config from form
   outputPath     String?
+  appId          String?
+  app            App?            @relation(fields: [appId], references: [id])
   createdAt      DateTime        @default(now())
   updatedAt      DateTime        @updatedAt
   agentRuns      AgentRun[]