No explicit connection pool size

[jeesunikim]

• Location: src/utils/connect.ts:93, src/utils/connect.ts:132
• Vulnerability: Prisma defaults to num_cpus * 2 + 1 connections. In a container with 1 vCPU, that's only 3 connections. Under sustained load, this is easily exhausted.
• Exploit scenario: An attacker sends bursts of requests just under the rate limit (1000/15min = ~1.1/sec). With only 3 pool connections and no statement timeout, even moderate query latency causes queuing and eventual timeouts.
• Impact: API becomes unresponsive under moderate load.
• Suggested fix: Set pool size explicitly via the connection URL: postgresql://...?connection_limit=20