feat: Add isAvailable field to AgentProfile model and DTO for managing agent availability status.

prisma/schema.prisma

@@ -174,6 +174,7 @@ model AgentProfile {
   profileCompleteness Int      @default(0)
   isPublic            Boolean  @default(true)
   isFeatured          Boolean  @default(false)
+  isAvailable         Boolean  @default(true)  // Agent availability status for connect requests
 
   // Stats (denormalized for performance)
   totalReviews        Int      @default(0)
@@ -196,6 +197,7 @@ model AgentProfile {
   @@index([verificationStatus])
   @@index([isPublic])
   @@index([isFeatured])
+  @@index([isAvailable])
   @@map("agent_profiles")
 }