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>

src/Web.h

@@ -6,8 +6,9 @@
 #ifndef webserver_h
 #define webserver_h
 
-#define WEB_CMD_QUEUE_SIZE 8
-#define WEB_CMD_TIMEOUT_MS 3000
+// Commands are queued by the async web server and drained by the main loop.
+// Big enough for Home Assistant firing a command at every shade at once.
+#define WEB_CMD_QUEUE_SIZE 32
 
 enum class web_cmd_t : uint8_t {
     shade_command,      // moveToTarget or sendCommand
@@ -18,6 +19,8 @@ enum class web_cmd_t : uint8_t {
     set_positions,      // set shade position directly
     shade_sensor,       // shade sensor command
     group_sensor,       // group sensor command
+    set_my_position,    // shade setMyPosition (position/tiltPosition)
+    unpair_shade,       // shade unpair (Prog) and clear paired flag
 };
 
 struct web_command_t {
@@ -67,8 +70,8 @@ class Web {
     void handleBackup(AsyncWebServerRequest *request);
     void handleReboot(AsyncWebServerRequest *request);
     void handleNotFound(AsyncWebServerRequest *request);
+    bool queueCommand(const web_command_t &cmd);
   private:
     void processQueue();
-    bool queueCommand(const web_command_t &cmd);
 };
 #endif