fix(redis-streams): use blocking connection pool for redis-py 8 compatibility

[pcanto-hopeit]

This PR updates hopeit.redis_streams.RedisStreamManager to use redis.asyncio.connection.BlockingConnectionPool instead of the default async Redis connection pool.

It also exposes Redis stream pool settings through StreamsConfig:

• max_connections, default 100
• blocking_pool_timeout, default 20.0
• protocol, default 2

Problem

With redis==7.4.1, the default async ConnectionPool effectively allowed a very high number of connections.

With redis==8.0.0, the default changed to 100. Since the regular pool raises immediately when exhausted, concurrent Redis Stream writes can fail with:

redis.exceptions.MaxConnectionsError: Too many connections

This can happen when Hopeit publishes an event result or downstream event through write_stream(...), specifically during XADD.

Fix

Fixes #222

RedisStreamManager now creates separate read and write Redis clients backed by BlockingConnectionPool.

When the pool reaches max_connections, concurrent operations wait up to blocking_pool_timeout for an available connection instead of failing immediately.

The Redis client shutdown path was also updated to use aclose(close_connection_pool=True) when available, with a fallback to close().

Tests

Added unit coverage for:

• Redis stream client creation using BlockingConnectionPool
• passing max_connections, blocking_pool_timeout, and protocol
• concurrent write_stream(...) calls with low max_connections
• closing read/write clients cleanly