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/app_main.c

@@ -1,7 +1,7 @@
 // Quantumancy ESP32-P4 Sensor Node — entry point.
 //
 // UNVERIFIED AGAINST REAL HARDWARE. Nobody working on this workstream has a
-// physical ESP32-P4 (or the BME280 / LD2410 modules) to flash and test
+// physical ESP32-P4 (or the BMP280 / RD-03E modules) to flash and test
 // against. This firmware is real, structurally-sound ESP-IDF C, reasoned
 // about carefully against ESP-IDF's documented APIs and the public
 // datasheets/protocol docs for each sensor -- but "compiles and reads