BDLMiner 2.5.6

BDLMiner V2 2.5.6

Completes digest-word polling for hardware SHA-256 on ESP32-S2, ESP32-S3 and
ESP32-C3. Mining results and the user interface are unchanged from
2.5.5.

• Use the digest word as the completion signal. The resumable SHA mining
  loops now poll word 7 of the digest instead of waiting only on the engine's
  busy flag. Once the word is nonzero, its value is reused for the target
  comparison, avoiding a separate read.
• Handle a zero final word. A completed digest may have a zero most-
  significant word. The poll periodically checks the engine's busy state so
  this valid result is recognized without an unbounded wait.
• The change applies to the resumable SHA engine used by ESP32-S2, ESP32-S3 and
  ESP32-C3. The classic ESP32 SHA assembly path is unchanged.

Validation

The complete host test suite passes, including exact digest and target-filter
checks for the resumable SHA kernels and the ESP32-S3 overlapped kernel. The
release workflow builds and validates the firmware images for all release
environments before creating the signed draft.

Full Changelog: v2.5.5...v2.5.6