Auto-load PRG files into VICE memory

## Description

The most common C64 development workflow is: compile a `.prg`, load it into VICE, and debug. Currently this requires manual steps outside Ghidra.

## Proposed implementation

- Add a `load_prg` remote method that:
1. Accepts a file path (or reads from the current Ghidra program)
2. Parses the 2-byte little-endian load address header
3. Writes the payload into VICE memory via `memory_set`
4. Optionally sets PC to the load address
5. Refreshes the trace memory view
- Could also add a launcher parameter (`OPT_PRG_FILE`) to auto-load on connect

## Why this matters

This eliminates the most tedious manual step in the C64 debug workflow and ties Ghidra directly into the build-load-debug cycle.