feat(api): add character_equipment table and entity

apps/api/src/database/migrations/equipment.migration.spec.ts

@@ -0,0 +1,52 @@
+import 'reflect-metadata';
+import { getMetadataArgsStorage } from 'typeorm';
+import { CharacterEquipment } from '../../equipment/entities/character-equipment.entity';
+
+describe('character_equipment schema', () => {
+  it('stores slot as a non-nullable equipment_slot_enum column', () => {
+    const metadata = getMetadataArgsStorage();
+    const column = metadata.columns.find(
+      (candidate) =>
+        candidate.target === CharacterEquipment && candidate.propertyName === 'slot',
+    );
+
+    expect(column).toBeDefined();
+    expect(column?.options.type).toBe('enum');
+    expect(column?.options.enumName).toBe('equipment_slot_enum');
+    expect(column?.options.nullable).toBeFalsy();
+  });
+
+  it('enforces one equipped item per character per slot', () => {
+    const metadata = getMetadataArgsStorage();
+    const index = metadata.indices.find(
+      (candidate) =>
+        candidate.target === CharacterEquipment &&
+        candidate.columns?.includes('characterId') &&
+        candidate.columns?.includes('slot'),
+    );
+
+    expect(index).toBeDefined();
+    const indexMetadata = index as typeof index & {
+      options?: { unique?: boolean };
+      unique?: boolean;
+    };
+    expect(indexMetadata?.options?.unique ?? indexMetadata?.unique).toBe(true);
+  });
+
+  it('forbids one CharacterItem from occupying more than one equipment slot', () => {
+    const metadata = getMetadataArgsStorage();
+    const index = metadata.indices.find(
+      (candidate) =>
+        candidate.target === CharacterEquipment &&
+        candidate.columns?.length === 1 &&
+        candidate.columns?.includes('characterItemId'),
+    );
+
+    expect(index).toBeDefined();
+    const indexMetadata = index as typeof index & {
+      options?: { unique?: boolean };
+      unique?: boolean;
+    };
+    expect(indexMetadata?.options?.unique ?? indexMetadata?.unique).toBe(true);
+  });
+});