Added redis caching to prevent label duplication #1

This commit introduces Redis caching to prevent redundant moderation
actions, reducing the load on the Bluesky API.

- Added the `redis` package as a dependency. - Implemented
`connectRedis` and `disconnectRedis` functions to manage the Redis
connection. - Added `tryClaimPostLabel`, `tryClaimAccountLabel`, and
`tryClaimAccountComment` functions to manage and claim resources for
caching purposes. - Modified `src/config.ts` to include the `REDIS_URL`
environment variable. - Added `src/redis.ts` which contains the Redis
client and connection management. - Integrated the caching logic into
moderation functions to ensure that actions are performed only once per
resource. - Added Redis healthcheck to compose.yaml. - Updated
package.json and bun.lock.