v0.21.3 — the logo is transparent

No code change.

Both copies of the mark were the old export on a white background with no alpha channel, so both wore a white rectangle wherever the page behind them was not white: assets/vgi-logo.png, which the README links and the javadoc task copies into the generated docs, and the data: URI inlined in the landing page the library serves.

Both are now cut from a committed master by scripts/regenerate_logo_assets.py. The inlined copy is palettized to 256 colours — flat artwork, so visually indistinguishable from truecolour, and it holds the base64 packaged into every jar at 20 KiB rather than 99 KiB.

The version moves because that landing page is a packaged resource: republishing is the only way the new mark reaches anyone running this server.