Update project documentation for database integration

- Update README.md with database setup instructions and path alias usage
- Add comprehensive database connection and migration instructions
- Document TypeScript path aliases with clear usage examples
- Update .github/copilot-instructions.md with current project state
- Remove outdated TODOs related to database implementation
- Update Next Steps section to focus on UI implementation tasks
- Add guidelines for handling Prisma Decimal types with proper conversion
- Improve developer onboarding with clearer setup instructions

README.md

@@ -1,4 +1,4 @@
-# My Bank App - Financial Transaction Manager
+# Financial Transaction Manager
 
 A web application for managing financial transactions across multiple bank accounts.
 
@@ -7,7 +7,7 @@ A web application for managing financial transactions across multiple bank accou
 *   **Purpose:** Provides a user interface for CRUD operations on financial transactions.
 *   **Technology:** Built with Astro, TypeScript, and plain CSS, utilizing Astro API routes.
 *   **Layout:** Features a two-column dashboard design with a sidebar for account selection/actions and a main area for transaction display.
-*   **Data Management:** Currently uses an in-memory data store (`src/data/store.ts`) accessed via API endpoints (`src/pages/api/`).
+*   **Data Management:** Uses Prisma ORM for database operations (`src/data/db.service.ts`), accessed via API endpoints (`src/pages/api/`).
 *   **Key Features (Implemented & Planned):** Account switching, transaction listing, adding, editing, and deleting transactions.
 
 ## Logs
@@ -33,6 +33,52 @@ The MCP server will automatically start when you open the project in a devcontai
 
 ### Database Setup
 
+The project uses Prisma ORM for database operations. To set up the database:
+
+1. Create a `.env` file in the project root with your database connection string:
+   ```
+   DATABASE_URL="postgresql://username:password@localhost:5432/finance"
+   ```
+
+2. Run database migrations:
+   ```bash
+   npx prisma migrate dev
+   ```
+
+3. Seed the database with initial data (optional):
+   ```bash
+   npx prisma db seed
+   ```
+
+4. To view and manage your data visually:
+   ```bash
+   npx prisma studio
+   ```
+
+## Path Aliases
+
+This project uses TypeScript path aliases for cleaner imports. Instead of using relative paths like `../../../../data/db.service`, use the following aliases:
+
+- `@/*` - Maps to `src/*`
+- `@components/*` - Maps to `src/components/*`
+- `@layouts/*` - Maps to `src/layouts/*`
+- `@data/*` - Maps to `src/data/*`
+- `@pages/*` - Maps to `src/pages/*`
+- `@styles/*` - Maps to `src/styles/*`
+- `@stores/*` - Maps to `src/stores/*`
+- `@utils/*` - Maps to `src/utils.ts`
+- `@types` - Maps to `src/types.ts`
+
+Example:
+```typescript
+// ✅ DO use path aliases like this
+import { transactionService } from '@data/db.service';
+import type { Transaction } from '@types';
+
+// ❌ DON'T use relative imports like this
+import { transactionService } from '../../../../data/db.service';
+```
+
 ## Development Container Setup
 
 ### GitHub Personal Access Token