OTAFIX 2.4.1 Preview 3 - restored BLE throughput

This preview supersedes Preview 2 for testing while preserving the earlier releases and tags.

Changes since Preview 2:

• Restore the upstream OTAFIX 10 ms minimum BLE connection interval.
• Restore zero BLE slave latency, addressing the observed OTA throughput regression from approximately 5.4 kB/s to 1.4 kB/s.
• Retain the Preview 2 DFU validation, clean BLE reboot, and USB-first recovery improvements.

Direct UF2 downloads:

• Heltec T096
• Heltec T114

Validation completed with successful CMake builds for heltec_t096 and heltec_t114.