feat: add batch insert operations to repositories (refs #26)

Add batchInsert methods to vehicles, fuel-logs, maintenance, and documents repositories. Multi-value INSERT syntax provides 10-100x performance improvement over individual operations for bulk data import.

- vehicles.repository: batchInsert for vehicles
- fuel-logs.repository: batchInsert for fuel logs
- maintenance.repository: batchInsertRecords and batchInsertSchedules
- documents.repository: batchInsert for documents
- All methods support empty array (immediate return) and optional transaction client
- Fix lint error: replace require() with ES6 import in test mock

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

backend/src/features/vehicles/data/vehicles.repository.ts

@@ -164,6 +164,57 @@ export class VehiclesRepository {
     return this.mapRow(result.rows[0]);
   }
 
+  async batchInsert(
+    vehicles: Array<CreateVehicleRequest & { userId: string, make?: string, model?: string, year?: number }>,
+    client?: any
+  ): Promise<Vehicle[]> {
+    if (vehicles.length === 0) {
+      return [];
+    }
+
+    // Multi-value INSERT for performance (avoids N round-trips)
+    const queryClient = client || this.pool;
+    const placeholders: string[] = [];
+    const values: any[] = [];
+    let paramCount = 1;
+
+    vehicles.forEach((vehicle) => {
+      const vehicleParams = [
+        vehicle.userId,
+        (vehicle.vin && vehicle.vin.trim().length > 0) ? vehicle.vin.trim() : null,
+        vehicle.make,
+        vehicle.model,
+        vehicle.year,
+        vehicle.engine,
+        vehicle.transmission,
+        vehicle.trimLevel,
+        vehicle.driveType,
+        vehicle.fuelType,
+        vehicle.nickname,
+        vehicle.color,
+        vehicle.licensePlate,
+        vehicle.odometerReading || 0
+      ];
+
+      const placeholder = `($${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++})`;
+      placeholders.push(placeholder);
+      values.push(...vehicleParams);
+    });
+
+    const query = `
+      INSERT INTO vehicles (
+        user_id, vin, make, model, year,
+        engine, transmission, trim_level, drive_type, fuel_type,
+        nickname, color, license_plate, odometer_reading
+      )
+      VALUES ${placeholders.join(', ')}
+      RETURNING *
+    `;
+
+    const result = await queryClient.query(query, values);
+    return result.rows.map((row: any) => this.mapRow(row));
+  }
+
   async softDelete(id: string): Promise<boolean> {
     const query = `
       UPDATE vehicles

backend/src/features/vehicles/tests/integration/vehicles.integration.test.ts

@@ -12,9 +12,8 @@ import fastifyPlugin from 'fastify-plugin';
 
 // Mock auth plugin to bypass JWT validation in tests
 jest.mock('../../../../core/plugins/auth.plugin', () => {
-  const fp = require('fastify-plugin');
   return {
-    default: fp(async function(fastify: any) {
+    default: fastifyPlugin(async function(fastify: any) {
       fastify.decorate('authenticate', async function(request: any, _reply: any) {
         request.user = { sub: 'test-user-123' };
       });