v1.5.8

Changes

• Fix MQTT subscription topic validation to reject malformed UTF-8 and null characters.
• Fix QoS2 inflight and retry bookkeeping races, including retry timestamp updates without holding connection locks during writes.
• Prevent retained messages from being resent across unrelated subscribe batches.
• Add locking around in-memory session provider count and close operations.
• Handle SIGTERM for graceful shutdown instead of registering the non-catchable SIGKILL.
• Update broker connection error wrapping and upgrade CI Go version to 1.25.x.
• Upgrade dependencies, including migrating Kafka bridge from github.com/Shopify/sarama to github.com/IBM/sarama v1.50.1.

Verification

• go test ./...
• go test -race ./broker ./broker/lib/sessions ./broker/lib/topics ./plugins/bridge