firmware: verify against actual target hardware, fix real conflicts

Researched the exact modules the user is building with and fixed three
concrete issues the earlier speculative firmware got wrong:

1. WiFi: confirmed the target board (Waveshare ESP32-P4-Module-DEV-KIT,
   chip ESP32-P4NRW32) bridges WiFi through an onboard ESP32-C6
   co-processor over a fixed 7-pin SDIO link (CLK18/CMD19/D0-14/D1-15/
   D2-16/D3-17/RESET54, cross-confirmed against Espressif's own
   esp-hosted-mcu docs). wifi_manager.c's esp_wifi_init()/esp_wifi_start()
   calls don't need to change — esp_wifi_remote/esp_hosted provide a
   drop-in-compatible API — but the component manifest (new
   main/idf_component.yml) and sdkconfig.defaults were missing entirely.

2. Real pin conflict: the presence sensor's original UART pins (17/18)
   directly collided with the SDIO CLK/D3 pins above — wiring it there
   would have broken WiFi, the sensor, or both. Moved to GPIO4/5.

3. Swapped placeholder parts for the user's actual hardware:
   - BME280 -> BMP280 (GY-BMP280 module): temp+pressure only, no humidity.
     Rewrote the driver rather than just renaming it — the old code would
     have read nonexistent humidity registers and reported garbage
     forever. 3.3V-only wiring note added (the BME280 assumption of
     5V-tolerant logic doesn't hold for this specific breakout).
   - LD2410 -> RD-03E (Ai-Thinker, not Hi-Link — a different manufacturer
     with a different, incompatible UART protocol). Rewrote the frame
     parser against the RD-03E's actual (if less-documented) 5-byte
     simple-report format. Reports numeric distance instead of a boolean,
     which better fits both the hardware's actual output and the backend's
     statistical anomaly detector.

README, CMakeLists.txt, and all cross-references updated to match.

firmware/esp32p4-sensor-node/main/sensor_registry.c

@@ -9,8 +9,8 @@
 
 #include <stdbool.h>
 #include "sensor_registry.h"
-#include "bme280.h"
-#include "ld2410.h"
+#include "bmp280.h"
+#include "rd03e.h"
 #include "esp_log.h"
 
 static const char *TAG = "sensor_registry";
@@ -19,8 +19,8 @@ static const char *TAG = "sensor_registry";
 // matters only for init() sequencing (e.g. bus setup before device use);
 // read() order just determines readings array ordering in the POST body.
 static const sensor_driver_t s_drivers[] = {
-    { .name = "bme280", .init = bme280_init, .read = bme280_read },
-    { .name = "ld2410", .init = ld2410_init, .read = ld2410_read },
+    { .name = "bmp280", .init = bmp280_init, .read = bmp280_read },
+    { .name = "rd03e", .init = rd03e_init, .read = rd03e_read },
     // Add new drivers here, e.g.:
     // { .name = "my_sensor", .init = my_sensor_init, .read = my_sensor_read },
 };