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/idf_component.yml

@@ -0,0 +1,14 @@
+# Managed component dependencies for the Quantumancy sensor node.
+#
+# esp_wifi_remote + esp_hosted: the ESP32-P4 has NO integrated Wi-Fi/BT
+# radio (confirmed against the target hardware — Waveshare
+# ESP32-P4-Module-DEV-KIT, chip ESP32-P4NRW32 — which pairs it with an
+# onboard ESP32-C6 co-processor reachable over SDIO). esp_wifi_remote
+# provides a drop-in-compatible esp_wifi_* API that transparently proxies
+# to the C6 over that SDIO link via esp_hosted's RPC layer — wifi_manager.c
+# calls the normal esp_wifi_init()/esp_wifi_start() and does not need to
+# know the radio isn't local. See README.md's Wi-Fi section for the SDIO
+# pin assignments this depends on and why they're reserved from sensor use.
+dependencies:
+  espressif/esp_wifi_remote: "*"
+  espressif/esp_hosted: "*"