feat: Day 8-9 - Project Management API completed

Backend:
- Create project routes (GET, POST, PUT, DELETE)
- Implement projectController with CRUD operations
- Create projectService for database operations
- Add validation middleware for request validation
- Update Prisma schema (add background, researchType, deletedAt fields)
- Implement soft delete for projects

Frontend:
- Create projectApi service module
- Update useProjectStore with fetchProjects and loading state
- Connect ProjectSelector to real API with loading indicator
- Connect CreateProjectDialog to real API with error handling
- Connect EditProjectDialog to real API with loading state
- Add comprehensive error handling and user feedback

Build: Both frontend and backend build successfully

backend/prisma/schema.prisma

@@ -50,17 +50,20 @@ model Project {
   id                String   @id @default(uuid())
   userId            String   @map("user_id")
   name              String
-  description       String   @db.Text
+  background        String   @default("") @db.Text
+  researchType      String   @default("observational") @map("research_type")
   conversationCount Int      @default(0) @map("conversation_count")
   
   createdAt         DateTime @default(now()) @map("created_at")
   updatedAt         DateTime @updatedAt @map("updated_at")
+  deletedAt         DateTime? @map("deleted_at")
   
   user              User     @relation(fields: [userId], references: [id], onDelete: Cascade)
   conversations     Conversation[]
   
   @@index([userId])
   @@index([createdAt])
+  @@index([deletedAt])
   @@map("projects")
 }