Pi port: serial transport, addressed ESP-NOW bridge, port 80

- Run app on Raspberry Pi: serial to ESP32 bridge at 912000 baud, /dev/ttyS0
- Remove ESP-NOW/MicroPython-only code from src (espnow, p2p, wifi, machine/Pin)
- Transport: always send 6-byte MAC + payload; optional to/destination_mac in API and WebSocket
- Settings and model DB use project paths (no root); fix sys.print_exception for CPython
- Preset/settings controllers use get_current_sender(); template paths for cwd=src
- Pipfile: run from src, PORT from env; scripts for port 80 (setcap) and test
- ESP32 bridge: receive 6-byte addr + payload, LRU peer management (20 max), handle ESP_ERR_ESPNOW_EXIST
- Add esp32/main.py, esp32/benchmark_peers.py, scripts/setup-port80.sh, scripts/test-port80.sh

Made-with: Cursor

src/models/serial.py

@@ -0,0 +1,12 @@
+class Serial:
+    def __init__(self, port, baudrate):
+        self.port = port
+        self.baudrate = baudrate
+        self.uart = UART(1, baudrate, tx=Pin(21), rx=Pin(6))
+
+    def send(self, data):
+        self.uart.write(data)
+
+    def receive(self):
+        return self.uart.read()
+