Apply infrastructure radio changes after a two-second reply handoff

Persist set freq and set radio atomically, then apply through the existing safe radio scheduler without rebooting. Retain the old tuple until the delay and reply handoff finish, including queued room/sensor replies and TX-complete callbacks. End temporary sessions when accepting a permanent change.

Display applied RF settings even when radio2 is off. Share radio validation across immediate and scheduled setters to preserve STM32 Mini flash capacity. Update command documentation, regression coverage, and CI.

Validated production timing, persistence, display, CLI, fleet/reply, RX, sleep and Morse regressions. W12 repeater, room-server and sensor builds pass. Canonical STM32 Mini Repeater passes flash and RAM admission with 448 bytes of flash remaining. Physical W12 RF testing was not performed.

docs/cli_command_availability.md

@@ -103,7 +103,7 @@ over the normal binary USB, BLE, or TCP connection:
 | [`get bootloader.ver`](cli_commands.md#view-the-bootloader-version-nrf52-only) | nRF52 Companion terminal and command `0x42`; unidentifiable metadata returns `unknown` |
 | [`get/set sdcard`](test-results/companion_cli_parity_2026-10-23.md#shared-sd-commands) | nRF52 builds with SD OTA storage; maintenance retains OTA and Ethernet ownership guards |
 | `erase` | Local terminal and binary command `0x42`; reboot after erasing stored settings |
-| `set freq <MHz>` | Local terminal, binary command `0x42`, and authorized LoRa CLI; reboot to apply |
+| `set freq <MHz>` | Local terminal, binary command `0x42`, and authorized LoRa CLI; applies automatically (infrastructure waits two seconds and for the reply to drain) |
 | [`get public.key`](cli_commands.md#view-this-nodes-public-key) | Companion text terminal and binary command `0x42`; read-only, no private-key export feature required |
 | `get prv.key` | Local terminal and binary command `0x42`; requires private key export enabled |
 | `get password` | ESP32 WiFi Companion reports management-password status without revealing it; other Companions report no admin password; infrastructure returns its password locally |