fix: switch backend to CommonJS, generate Drizzle migrations, add migrate script

- Remove "type": "module" and switch tsconfig to CommonJS/Node resolution
  to fix drizzle-kit ESM/CJS incompatibility
- Strip .js extensions from all backend TypeScript imports
- Fix gamification resolver: combine two .where() calls using and()
- Fix index.ts: wrap top-level awaits in async main(), fix Fastify+yoga
  request handling via handleNodeRequestAndResponse
- Generate initial Drizzle SQL migration (0000_pale_hellion.sql) for all
  15 tables
- Add src/scripts/migrate.ts: programmatic Drizzle migrator for production
- Copy migrations folder into Docker image (Dockerfile.backend)
- Add schema:migrate npm script

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/backend/src/graphql/resolvers/gamification.ts

@@ -1,7 +1,7 @@
-import { builder } from "../builder.js";
-import { LeaderboardEntryType, UserGamificationType, AchievementType } from "../types/index.js";
-import { user_stats, users, user_achievements, achievements, user_points } from "../../db/schema/index.js";
-import { eq, desc, gt, count, isNotNull } from "drizzle-orm";
+import { builder } from "../builder";
+import { LeaderboardEntryType, UserGamificationType, AchievementType } from "../types/index";
+import { user_stats, users, user_achievements, achievements, user_points } from "../../db/schema/index";
+import { eq, desc, gt, count, isNotNull, and } from "drizzle-orm";
 
 builder.queryField("leaderboard", (t) =>
   t.field({
@@ -73,8 +73,7 @@ builder.queryField("userGamification", (t) =>
         })
         .from(user_achievements)
         .leftJoin(achievements, eq(user_achievements.achievement_id, achievements.id))
-        .where(eq(user_achievements.user_id, args.userId))
-        .where(isNotNull(user_achievements.date_unlocked))
+        .where(and(eq(user_achievements.user_id, args.userId), isNotNull(user_achievements.date_unlocked)))
         .orderBy(desc(user_achievements.date_unlocked));
 
       const recentPoints = await ctx.db