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.

src/Dispatcher.cpp

@@ -1,4 +1,5 @@
 #include "Dispatcher.h"
+#include "helpers/ota/OtaTiming.h"
 
 #if MESH_PACKET_LOGGING
   #include <Arduino.h>
@@ -66,6 +67,7 @@ void Dispatcher::begin() {
   outbound_radio_retry_at = 0;
   outbound_radio_retry_pending = false;
   outbound_radio_retry_used = false;
+  ota_tx_airtime = 0;
   radio_nonrx_start = _ms->getMillis();
 
   duty_cycle_window_ms = getDutyCycleWindowMs();
@@ -376,6 +378,10 @@ void Dispatcher::loop() {
     } else if (_radio->isSendComplete()) {
       long t = _ms->getMillis() - outbound_start;
       total_air_time += t;
+      if (outbound->getPayloadType() == PAYLOAD_TYPE_OTA) {
+        ota_tx_finished_at = _ms->getMillis();
+        ota_tx_airtime = t > 0 ? (uint32_t)t : 0;
+      }
       //Serial.print("  airtime="); Serial.println(t);
 
       updateTxBudget();
@@ -707,6 +713,9 @@ void Dispatcher::processRecvPacket(Packet* pkt) {
 void Dispatcher::checkSend() {
   if (_radio->isCarrierWaveActive()) return;
   const uint32_t now = _ms->getMillis();
+  if (ota_tx_airtime && now - ota_tx_finished_at >= ota::packetQuietTime(ota_tx_airtime, getOtaSpeedFactor())) {
+    ota_tx_airtime = 0;
+  }
   uint32_t next_outbound;
   if (_mgr->getNextOutboundTime(now, next_outbound)) {
     if ((int32_t)(next_outbound - now) > 0) return;
@@ -724,6 +733,29 @@ void Dispatcher::checkSend() {
     failOutboundTransmit();
     return;
   }
+  if (ota_tx_airtime) {
+    const uint32_t gap = ota::packetQuietTime(ota_tx_airtime, getOtaSpeedFactor());
+    const uint32_t elapsed = now - ota_tx_finished_at;
+    if (elapsed >= gap) ota_tx_airtime = 0;
+    else if (pending && pending->getPayloadType() == PAYLOAD_TYPE_OTA) {
+      // Preserve this packet's priority and retry ownership. A short deferral
+      // lets ordinary traffic run and makes live speed changes take effect
+      // within 100 ms, even when the previous speed was much slower.
+      const uint32_t remaining = gap - elapsed;
+      int candidates = _mgr->getOutboundTotal();
+      do {
+        if (candidates-- <= 0 || !_mgr->deferOutboundForPacing(pending, now,
+            now + (remaining > 100 ? 100 : remaining))) return;
+        pending = _mgr->peekNextOutbound(now);
+      } while (pending && pending->getPayloadType() == PAYLOAD_TYPE_OTA);
+      if (!pending) return;
+      if (!isPacketRadioCurrent(pending)) {
+        outbound = _mgr->getNextOutbound(now);
+        failOutboundTransmit();
+        return;
+      }
+    }
+  }
   updateTxBudget();
   
   uint32_t est_airtime = pending && _radio->profiles()