feat(db): add core Drizzle schema tables (hardware, games, gameVersions)

- Create lib/db/schema/ directory with barrel export index.ts
- Add hardware table with device_type enum (handled/console)
- Add games table with Steam metadata, sync fields, and JSON genres
- Add game_versions table with composite unique (gameId, buildId) and cascade delete

Refs: Chunk 2 of database schema implementation

lib/db/schema/gameVersions.ts

@@ -0,0 +1,25 @@
+import {
+  boolean,
+  pgTable,
+  text,
+  timestamp,
+  unique,
+} from "drizzle-orm/pg-core"
+import { games } from "./games"
+
+export const gameVersions = pgTable(
+  "game_versions",
+  {
+    id: text("id")
+      .primaryKey()
+      .$defaultFn(() => crypto.randomUUID()),
+    gameId: text("game_id")
+      .notNull()
+      .references(() => games.id, { onDelete: "cascade" }),
+    buildId: text("build_id"),
+    versionString: text("version_string"),
+    isLatest: boolean("is_latest").default(false).notNull(),
+    createdAt: timestamp("created_at").defaultNow().notNull(),
+  },
+  (table) => [unique("game_build_unique").on(table.gameId, table.buildId)]
+)