Add persistent LoRa OTA speed control and harden timing

Add get/set ota.speed and OTA CLI aliases for factors from 0.05 to 3,
defaulting to the existing pace. Persist the setting independently of the
OTA workspace and apply it to OTA packet pacing, relays, discovery and
adverts while retaining the configured airtime budget.

Preserve physical proof/retry allowances, account for both participating
radio profiles, keep optional deadlines armed across millis rollover, and
exclude intentional pacing from observer stale-packet age. Keep local
verification at its normal rate and retain a valid saved speed if backup
recovery cannot finish. Add documentation and CI regression coverage.

Validation: 1,491 native tests and 26 CLI/integration tests passed. Built
ESP32 full repeater, ESP32 full Companion, nRF52 full Companion and STM32
USB Companion successfully, including their memory/size checks.

.github/workflows/run-unit-tests.yml

@@ -106,6 +106,7 @@ jobs:
           python3 -B test/test_repeater_radio_timing_integration.py
           python3 -B test/test_temp_radio_reply_delivery_contract.py
           python3 -B test/test_reply_tx_integration.py
+          python3 -B test/test_ota_speed.py -v
 
       - name: Verify dual-profile switching and chirp timing
         working-directory: test