Adds --screenshots argument to pebble publish --non-interactive command

[adrienthiery]

Summary

• Adds --screenshots FILE [FILE ...] argument to pebble publish
• In --non-interactive mode, accepts local screenshot/GIF files instead of requiring a running
  emulator
• Filenames must start with the platform name (e.g. emery_screenshot.png) to match the existing upload
  convention

Usage

  pebble publish --non-interactive \
    --description "My watchface" \
    --no-gif-all-platforms \
    --screenshots emery_screenshot.png basalt_screenshot.png emery_preview.gif

[ericmigi]

Nice addition! One small suggestion: the interactive path in _prompt_local_screenshot_files checks os.path.exists(path) before accepting each file, which gives the user a clear early error. The new --screenshots path skips that, so a typo in a filename won't surface until _append_capture_files tries to open() it during upload — by which point the error message is less obvious.

Maybe worth adding a quick existence check before the split:

local_files = getattr(args, "screenshots", None) or []
if local_files:
    for p in local_files:
        if not os.path.exists(p):
            raise ToolError("Screenshot file not found: {}".format(p))
    gif_paths = [p for p in local_files if p.lower().endswith(".gif")]
    screenshot_paths = [p for p in local_files if not p.lower().endswith(".gif")]

[ericmigi]

thanks!