fix: move radio TX to a dedicated task so HA WebSocket stays connected

Web command handlers ran on the async_tcp task and blocked up to 3s
waiting for loop() to bit-bang radio frames. async_tcp also services the
WebSocket on port 8080, so pongs stalled and Home Assistant
(ping_timeout=15) disconnected when several covers were commanded.

- Add a radio_tx FreeRTOS task with a job queue; sendFrame/repeatFrame
  and repeater frames enqueue instead of transmitting inline.
- Serialize CC1101 access with a recursive mutex (TX task, apply, end,
  frequency scan, RSSI read).
- Make Web::queueCommand fire-and-forget; drop the done semaphore.
- Route /setMyPosition and /unpairShade through the command queue.
- Clamp repeats to MAX_TX_REPEATS (40).
- Pin AsyncTCP to core 0 on dual-core targets.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

platformio.ini

@@ -39,14 +39,23 @@ monitor_filters =
 	esp32_exception_decoder
 	log2file
 
+; Dual-core targets: keep the async web/socket task on core 0 so the radio
+; task on core 1 (with loop()) never competes with network handling.
+[dualcore]
+build_flags =
+	${env.build_flags}
+	-DCONFIG_ASYNC_TCP_RUNNING_CORE=0
+
 [env:esp32dev]
 board = esp32dev
 board_build.partitions = esp32_3MB.csv
+build_flags = ${dualcore.build_flags}
 
 [env:esp32devdbg]
 board = esp32dev
 build_type = debug
 board_build.partitions = esp32_3MB.csv
+build_flags = ${dualcore.build_flags}
 
 [env:esp32c3]
 board = esp32-c3-devkitm-1
@@ -54,6 +63,7 @@ board_build.partitions = esp32_3MB.csv
 
 [env:esp32s3]
 board = esp32-s3-devkitc-1
+build_flags = ${dualcore.build_flags}
 
 [env:esp32c6]
 platform = https://github.com/pioarduino/platform-espressif32/releases/download/stable/platform-espressif32.zip