feat(loot): add item, loot table, and combat reward entities

Declares every new TypeORM entity Slice 0.4 needs (ItemDefinition,
CharacterItem, LootTable, LootTableEntry, CombatReward, CombatRewardItem)
plus the ItemType/EquipmentSlot/ItemRarity enums, and adds the two columns
existing entities gain: Character.silver and MonsterDefinition.lootTableId.
No migration SQL or service logic yet - just schema declarations backed by
a metadata-driven schema spec.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

apps/api/src/loot/entities/loot-table-entry.entity.ts

@@ -0,0 +1,63 @@
+import {
+  Column,
+  CreateDateColumn,
+  Entity,
+  Index,
+  JoinColumn,
+  ManyToOne,
+  PrimaryGeneratedColumn,
+  UpdateDateColumn,
+} from 'typeorm';
+import { ItemDefinition } from '../../items/entities/item-definition.entity';
+import { LootTable } from './loot-table.entity';
+
+/**
+ * One independently rolled drop (spec §17).
+ *
+ * `position` fixes the roll order so injected randoms are predictable in tests;
+ * it is content ordering, not priority. A guaranteed drop is simply
+ * `dropChance = 1.0000` — no extra mechanism needed (spec §14).
+ */
+@Entity({ name: 'loot_table_entries' })
+@Index('IDX_loot_table_entries_table_position', ['lootTableId', 'position'], { unique: true })
+@Index('IDX_loot_table_entries_table_item', ['lootTableId', 'itemDefinitionId'], { unique: true })
+export class LootTableEntry {
+  @PrimaryGeneratedColumn('uuid', { name: 'id' })
+  id!: string;
+
+  @Column({ name: 'loot_table_id', type: 'uuid' })
+  lootTableId!: string;
+
+  @Column({ name: 'item_definition_id', type: 'uuid' })
+  itemDefinitionId!: string;
+
+  @Column({ name: 'position', type: 'integer' })
+  position!: number;
+
+  // PostgreSQL numeric arrives as a string, like LocationConnection.ambushChance.
+  @Column({ name: 'drop_chance', type: 'numeric', precision: 5, scale: 4 })
+  dropChance!: string;
+
+  @Column({ name: 'min_quantity', type: 'integer' })
+  minQuantity!: number;
+
+  @Column({ name: 'max_quantity', type: 'integer' })
+  maxQuantity!: number;
+
+  @Column({ name: 'enabled', type: 'boolean' })
+  enabled!: boolean;
+
+  @CreateDateColumn({ name: 'created_at', type: 'timestamptz' })
+  createdAt!: Date;
+
+  @UpdateDateColumn({ name: 'updated_at', type: 'timestamptz' })
+  updatedAt!: Date;
+
+  @ManyToOne(() => LootTable, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'loot_table_id' })
+  lootTable!: LootTable;
+
+  @ManyToOne(() => ItemDefinition, { onDelete: 'RESTRICT' })
+  @JoinColumn({ name: 'item_definition_id' })
+  itemDefinition!: ItemDefinition;
+}