release.sh: build, package ZIP, tag, and create GitHub release in one command.
Screenshot slots now use 16:10 (matches Steam Deck's 1280x800 screen) with
object-contain so full-screen Deck captures fit without cropping.
The ZIP bundles plugin.json, main.py, package.json, dist/index.js (+ map) at
the archive root (no enclosing folder) — the format Decky's 'Install Plugin
from ZIP File' / 'Install Plugin from URL' expects.
Usage:
bun run build:zip # build + package → releases/plugin-v<version>.zip
bun run zip # package already-built dist only