Unified Hardware Canvas: extend laDecoders for both read and write

[vailuc]

Background

Currently every protocol module in laDecoders.ts exposes decode(...) functions. The canvas and decoder panel are read-only.

Goal

Extend the protocol architecture so each module exposes both decode(...) and encode(...) / write(...) functions. The same LA canvas and panel can then support observation and active control.

Why

This is the foundation for a visual chip programmer or debugger that sits on top of the existing decoder infrastructure instead of requiring a separate tool.

Acceptance criteria

• At least one decoder (e.g., UART or Modbus) has a symmetric encode or generate function that can produce a raw sample buffer from a frame description.
• The UI can toggle a channel between “input” and “output” without breaking the existing decoder view.
• No cloud or external telemetry dependencies are introduced.