feat(api): add character_equipment table and entity

apps/api/src/database/migrations/1789000000000-CreateEquipment.ts

@@ -0,0 +1,34 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+export class CreateEquipment1789000000000 implements MigrationInterface {
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    // Reuses the "equipment_slot_enum" type created by CreateLootAndRewards.
+    await queryRunner.query(`CREATE TABLE "character_equipment" (
+      "id" uuid NOT NULL DEFAULT gen_random_uuid(),
+      "character_id" uuid NOT NULL,
+      "slot" "equipment_slot_enum" NOT NULL,
+      "character_item_id" uuid NOT NULL,
+      "created_at" TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(),
+      "updated_at" TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(),
+      CONSTRAINT "PK_character_equipment" PRIMARY KEY ("id"),
+      CONSTRAINT "FK_character_equipment_character" FOREIGN KEY ("character_id") REFERENCES "characters"("id") ON DELETE CASCADE ON UPDATE NO ACTION,
+      CONSTRAINT "FK_character_equipment_character_item" FOREIGN KEY ("character_item_id") REFERENCES "character_items"("id") ON DELETE CASCADE ON UPDATE NO ACTION
+    )`);
+    await queryRunner.query(
+      'CREATE UNIQUE INDEX "IDX_character_equipment_character_slot" ON "character_equipment" ("character_id", "slot")',
+    );
+    await queryRunner.query(
+      'CREATE UNIQUE INDEX "IDX_character_equipment_character_item" ON "character_equipment" ("character_item_id")',
+    );
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      'DROP INDEX "IDX_character_equipment_character_item"',
+    );
+    await queryRunner.query(
+      'DROP INDEX "IDX_character_equipment_character_slot"',
+    );
+    await queryRunner.query('DROP TABLE "character_equipment"');
+  }
+}

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

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+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);
+  });
+});

apps/api/src/equipment/entities/character-equipment.entity.ts

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+import {
+  Column,
+  CreateDateColumn,
+  Entity,
+  Index,
+  JoinColumn,
+  ManyToOne,
+  PrimaryGeneratedColumn,
+  UpdateDateColumn,
+} from 'typeorm';
+import { Character } from '../../characters/entities/character.entity';
+import { CharacterItem } from '../../items/entities/character-item.entity';
+import { EquipmentSlot } from '../../items/equipment-slot.enum';
+
+/**
+ * One equipped item in one slot for one character (spec §12).
+ *
+ * `characterItemId` must belong to `characterId` — enforced by
+ * `EquipmentService`, never by the client (spec §13).
+ */
+@Entity({ name: 'character_equipment' })
+@Index('IDX_character_equipment_character_slot', ['characterId', 'slot'], {
+  unique: true,
+})
+@Index('IDX_character_equipment_character_item', ['characterItemId'], {
+  unique: true,
+})
+export class CharacterEquipment {
+  @PrimaryGeneratedColumn('uuid', { name: 'id' })
+  id!: string;
+
+  @Column({ name: 'character_id', type: 'uuid' })
+  characterId!: string;
+
+  @Column({
+    name: 'slot',
+    type: 'enum',
+    enum: EquipmentSlot,
+    enumName: 'equipment_slot_enum',
+  })
+  slot!: EquipmentSlot;
+
+  @Column({ name: 'character_item_id', type: 'uuid' })
+  characterItemId!: string;
+
+  @CreateDateColumn({ name: 'created_at', type: 'timestamptz' })
+  createdAt!: Date;
+
+  @UpdateDateColumn({ name: 'updated_at', type: 'timestamptz' })
+  updatedAt!: Date;
+
+  @ManyToOne(() => Character, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'character_id' })
+  character!: Character;
+
+  @ManyToOne(() => CharacterItem, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'character_item_id' })
+  characterItem!: CharacterItem;
+}