fix: Redis cache, BullMQ webhook queue, pg_trgm migration, Prisma pool tuning (#775 #776 #777 #778)

[trinnode]

Summary

This PR addresses four backend infrastructure issues in a single focused changeset:

#775 — Replace in-process leaderboard LRU cache with Redis

• Added ioredis as a dependency
• Created src/services/redis.ts — shared Redis client constructed from REDIS_URL env var with graceful fallback to in-process cache when Redis is unavailable (local dev still works out of the box)
• Updated getCachedLeaderboard, setCachedLeaderboard, and invalidateProfileLeaderboardCache to use redis.get/redis.setex/redis.del when Redis is available, falling back to the existing in-process Map cache
• Cache invalidation across processes is now possible when a new transaction arrives

#776 — Replace DB-polled webhook delivery with BullMQ job queue

• Added bullmq as a dependency
• Created src/services/webhook-queue.ts — BullMQ queue and worker with:
  • Built-in exponential backoff: { attempts: 4, backoff: { type: 'exponential', delay: 1000 } }
  • Concurrency control (5 concurrent workers, 10 jobs/second rate limit)
  • DB delivery log kept in sync via worker lifecycle hooks
• Updated webhook-processor.ts to start a BullMQ worker when Redis is available, falling back to the existing DB-polled processor for local dev
• Webhook deliveries are now enqueued immediately in BullMQ when created, eliminating poll-interval latency

#777 — Add pg_trgm extension creation to Prisma migration

• The pg_trgm extension migration already exists at prisma/migrations/20260627000000_add_pg_trgm_extension/ — no additional changes needed

#778 — Expose Prisma connection pool size via environment variable

• Updated src/db.ts to construct DATABASE_URL with connection_limit and pool_timeout search params from env vars
• Added DATABASE_POOL_SIZE (default: 10, recommended: 20 for production) and DATABASE_POOL_TIMEOUT (default: 10 seconds) to .env.example
• Requests now return 503 when the pool is exhausted instead of silently queuing

Additional fixes (pre-existing)

• Fixed missing v1Router.get("/supporters/:address", ...) handler declaration that prevented compilation
• Fixed webhook.secret → webhook.secretHash to match the Prisma schema field name
• Fixed minor TS errors in test files that prevented clean builds

Test Results

• Build passes cleanly (tsc -p tsconfig.json — zero errors, improved from 2 pre-existing syntax errors)
• 99 tests pass, 13 fail (all pre-existing failures unrelated to this PR — same tests fail on the main branch)
• Redis fallback verified: when REDIS_URL is not set, all features gracefully fall back to in-process cache and DB-polled processor

Dependencies Added

• ioredis — Redis client
• bullmq — job queue built on Redis

Closes #775
Closes #776
Closes #777
Closes #778

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