fix: four real firmware defects found in adversarial review

rd03e.c: RD03E_FRAME_LEN was 5 but the frame's own documented layout
(header + gesture + distance_lo + distance_hi + footer[2]) is 6 bytes.
The footer check read buf[i+3], colliding with the distance high byte at
that same index — so every frame that validated at all was forced to have
distance_cm = lo | 0x5500 (~218m) regardless of what the sensor reported.
Distance readings were garbage 100% of the time, not intermittently.

mems_mic.c: i2s_del_channel() was missing on 2 of 3 init failure paths,
leaking the channel handle.

bmp280.c: the I2C bus/device handles leaked on 4 of 5 init failure paths;
added a fail label that releases both.

app_main.c: sensors now init before Wi-Fi bring-up, matching the rationale
sensor_driver.h already documents (a hanging sensor bus must not be able to
block network bring-up).

rtlsdr_experimental.c: rtlsdr_exp_stop() waited 500ms before
usb_host_uninstall(), but the daemon task blocks up to 1000ms inside
usb_host_lib_handle_events() before re-checking its running flag — the
delay must exceed that or teardown races a live daemon task.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

firmware/esp32p4-sensor-node/components/rtlsdr_experimental/rtlsdr_experimental.c

@@ -897,10 +897,14 @@ esp_err_t rtlsdr_exp_stop(rtlsdr_exp_handle_t h)
 
     h->running = false;
     /* Tasks self-delete once they observe h->running == false; give them a
-     * moment. A production version should use task-completion notification
-     * instead of a fixed delay — left as a TODO, not hardware-dependent but
-     * still unverified/untuned. */
-    vTaskDelay(pdMS_TO_TICKS(500));
+     * moment. The daemon task blocks up to 1000ms per iteration inside
+     * usb_host_lib_handle_events() before it re-checks h->running, so this
+     * delay must exceed that or usb_host_uninstall() below can race a still
+     * -running daemon task still holding the USB host lib open. A production
+     * version should use task-completion notification instead of a fixed
+     * delay — left as a TODO, not hardware-dependent but still
+     * unverified/untuned. */
+    vTaskDelay(pdMS_TO_TICKS(1200));
 
     usb_host_uninstall(); /* see rtlsdr_exp_start() note re: sole USB client assumption */
     return ESP_OK;