feat(api): add character_equipment table and entity

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

@@ -0,0 +1,59 @@
+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;
+}