feat: implement KM-based maintenance scheduling

Add maintenance intervals configuration to track maintenance by kilometers
driven. When a maintenance is marked COMPLETED, automatically calculate and
schedule the next maintenance based on interval + current odometer reading.

Features:
- MaintenanceInterval entity: stores KM/day intervals per vehicle & type
- scheduleNextMaintenance(): creates next SCHEDULED item after completion
- nextDueKm field: tracks when next maintenance is due (in kilometers)
- getDueBoard() queries already support KM-based tracking

Maintenance now "marches forward" based on distance driven, not just dates.
Each vehicle type can have different intervals (e.g., oil every 10k km, tires 50k km).

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

apps/edr-freight-api/src/migrations/2800000000000-AddMaintenanceIntervals.ts

@@ -0,0 +1,103 @@
+import { MigrationInterface, QueryRunner, Table, TableIndex, TableForeignKey, TableUnique } from 'typeorm';
+
+export class AddMaintenanceIntervals2800000000000 implements MigrationInterface {
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.createTable(
+      new Table({
+        name: 'maintenance_intervals',
+        schema: 'freight',
+        columns: [
+          {
+            name: 'id',
+            type: 'uuid',
+            isPrimary: true,
+            generationStrategy: 'uuid',
+            default: 'gen_random_uuid()',
+          },
+          {
+            name: 'vehicle_id',
+            type: 'uuid',
+            isNullable: false,
+          },
+          {
+            name: 'maintenance_type',
+            type: 'varchar',
+            isNullable: false,
+          },
+          {
+            name: 'interval_km',
+            type: 'numeric',
+            precision: 14,
+            scale: 2,
+            isNullable: true,
+          },
+          {
+            name: 'interval_days',
+            type: 'integer',
+            isNullable: true,
+          },
+          {
+            name: 'description',
+            type: 'text',
+            isNullable: true,
+          },
+          {
+            name: 'is_active',
+            type: 'boolean',
+            default: true,
+          },
+          {
+            name: 'created_at',
+            type: 'timestamptz',
+            default: 'now()',
+          },
+          {
+            name: 'updated_at',
+            type: 'timestamptz',
+            default: 'now()',
+          },
+          {
+            name: 'deleted_at',
+            type: 'timestamptz',
+            isNullable: true,
+          },
+        ],
+      }),
+    );
+
+    // Add indexes
+    await queryRunner.createIndex(
+      new Table({ name: 'maintenance_intervals', schema: 'freight' }),
+      new TableIndex({
+        name: 'IDX_maintenance_intervals_vehicle_type',
+        columnNames: ['vehicle_id', 'maintenance_type'],
+      }),
+    );
+
+    // Add unique constraint
+    await queryRunner.createUniqueConstraint(
+      'maintenance_intervals',
+      new TableUnique({
+        name: 'UQ_maintenance_intervals_vehicle_type',
+        columnNames: ['vehicle_id', 'maintenance_type'],
+      }),
+    );
+
+    // Add foreign key
+    await queryRunner.createForeignKey(
+      'maintenance_intervals',
+      new TableForeignKey({
+        name: 'FK_maintenance_intervals_vehicle',
+        columnNames: ['vehicle_id'],
+        referencedSchema: 'freight',
+        referencedTableName: 'vehicles',
+        referencedColumnNames: ['id'],
+        onDelete: 'CASCADE',
+      }),
+    );
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.dropTable('maintenance_intervals', true, true, true);
+  }
+}