Fix Prisma memory leak and add configurable connection pool

[tsurbs]

Summary

This PR addresses memory issues in Railway by implementing the Prisma singleton pattern and adding configurable connection pool sizing.

Changes

• Default connection pool size reduced from 10 to 3 connections
• Added PRISMA_CONNECTION_LIMIT environment variable to override the default
• Automatically appends connection_limit to DATABASE_URL if not already set
• Implements Prisma singleton pattern using globalThis to prevent multiple instances

Why This Matters

In containerized environments like Railway:

• Each PrismaClient instance opens its own connection pool (default: 10 connections)
• Multiple instances can accumulate during container restarts or hot reloads
• Each connection consumes memory for buffering
• Smaller containers (512MB-1GB) can quickly run out of memory

Configuration

Set the PRISMA_CONNECTION_LIMIT environment variable in Railway to adjust:

PRISMA_CONNECTION_LIMIT=3  # for 512MB containers
PRISMA_CONNECTION_LIMIT=5  # for 1GB+ containers

Or set it directly in your DATABASE_URL:

postgresql://...?connection_limit=3

Testing

• Code compiles successfully
• Connection pool limit is correctly applied
• Environment variable override works as expected

Fixes memory issues observed in Railway deployment.

[tsurbs]

This was bark, I have not verified