refactor(db): split schema into domain modules

Split the 276-line schema.ts into focused domain modules:
- users.ts: classes, users, userTimers (core identity)
- inventory.ts: items, inventory (item system)
- economy.ts: transactions, itemTransactions (currency flow)
- quests.ts: quests, userQuests (quest system)
- moderation.ts: moderationCases, lootdrops (moderation)

Original schema.ts now re-exports from schema/index.ts for backward
compatibility. All existing imports continue to work.

shared/db/schema/economy.ts

@@ -0,0 +1,69 @@
+import {
+    pgTable,
+    bigint,
+    varchar,
+    text,
+    timestamp,
+    bigserial,
+    index,
+    integer,
+} from 'drizzle-orm/pg-core';
+import { relations, type InferSelectModel } from 'drizzle-orm';
+import { users } from './users';
+import { items } from './inventory';
+
+// --- TYPES ---
+export type Transaction = InferSelectModel<typeof transactions>;
+export type ItemTransaction = InferSelectModel<typeof itemTransactions>;
+
+// --- TABLES ---
+export const transactions = pgTable('transactions', {
+    id: bigserial('id', { mode: 'bigint' }).primaryKey(),
+    userId: bigint('user_id', { mode: 'bigint' })
+        .references(() => users.id, { onDelete: 'cascade' }),
+    relatedUserId: bigint('related_user_id', { mode: 'bigint' })
+        .references(() => users.id, { onDelete: 'set null' }),
+    amount: bigint('amount', { mode: 'bigint' }).notNull(),
+    type: varchar('type', { length: 50 }).notNull(),
+    description: text('description'),
+    createdAt: timestamp('created_at', { withTimezone: true }).defaultNow(),
+}, (table) => [
+    index('transactions_created_at_idx').on(table.createdAt),
+]);
+
+export const itemTransactions = pgTable('item_transactions', {
+    id: bigserial('id', { mode: 'bigint' }).primaryKey(),
+    userId: bigint('user_id', { mode: 'bigint' })
+        .references(() => users.id, { onDelete: 'cascade' }).notNull(),
+    relatedUserId: bigint('related_user_id', { mode: 'bigint' })
+        .references(() => users.id, { onDelete: 'set null' }),
+    itemId: integer('item_id')
+        .references(() => items.id, { onDelete: 'cascade' }).notNull(),
+    quantity: bigint('quantity', { mode: 'bigint' }).notNull(),
+    type: varchar('type', { length: 50 }).notNull(), // e.g., 'TRADE', 'SHOP_BUY', 'DROP'
+    description: text('description'),
+    createdAt: timestamp('created_at', { withTimezone: true }).defaultNow(),
+});
+
+// --- RELATIONS ---
+export const transactionsRelations = relations(transactions, ({ one }) => ({
+    user: one(users, {
+        fields: [transactions.userId],
+        references: [users.id],
+    }),
+}));
+
+export const itemTransactionsRelations = relations(itemTransactions, ({ one }) => ({
+    user: one(users, {
+        fields: [itemTransactions.userId],
+        references: [users.id],
+    }),
+    relatedUser: one(users, {
+        fields: [itemTransactions.relatedUserId],
+        references: [users.id],
+    }),
+    item: one(items, {
+        fields: [itemTransactions.itemId],
+        references: [items.id],
+    }),
+}));