Feature/serial connection

[Outrun207]

Am successfully running this off of my Raspberry Pi. Powering and connecting to the radio via USB.

Summary

Adds the ability to connect to Meshtastic radios via serial/USB, in addition to the existing Bluetooth and WiFi options.
Serial devices appear as clickable buttons in the web UI — no need to type a path manually.

Why

The Raspberry Pi's onboard Bluetooth adapter has known issues with the SimpleBLE library (frequent scan stop failed
crashes). Serial/USB is a more reliable alternative when the radio is physically connected.

Changes

• api/src/lib/serialConnection.ts — New NodeSerialConnection class that implements the Meshtastic protobuf-over-serial
  protocol (0x94 0xc3 framing) using the serialport npm package
• api/src/lib/serial.ts — Serial port detection/listing utility
• api/src/index.ts — Added /serialPorts endpoint and startup port scan
• api/src/meshtastic.ts — connect() now detects serial paths (e.g. /dev/ttyACM0) and routes to the serial connection
• ui/src/Serial.svelte — New UI component showing available serial devices as clickable buttons
• ui/src/App.svelte — Added Serial component to the layout
• ui/src/Channels.svelte / ui/src/Message.svelte — Show friendly channel names instead of "Channel 0"

Usage

Connect a Meshtastic radio via USB. It will appear in the web UI under "Serial Devices". Click to connect. Or set
ADDRESS=/dev/ttyACM0 as an environment variable for auto-connect on startup.

[aaronsilber]

@Outrun207 I am not an official reviewer but in order to expedite merging this change, my suggestion would be to back out the README.md changes here that pertain to the proposed new Docker container, as that feels out of scope for "adding serial support" unless I am missing something. I would encourage creating a separate PR for the Docker container, one that includes the build spec for the container so it can be adopted into the project completely.

[Soltares]

Thank you @Outrun207 for the PR submission! I agree with @aaronsilber regarding the Docker container being a separate PR and integrated into the project. I will try to find time to fully review this as it is a big value-add. My concerns are mainly around how well the serialport dependency will package into the distributable for each respective platform.