v1.1.0: new, doctor, plugin install, sharper errors

Added

• motion new <name> [template]: start a scene from a two-box starter or from an example (architecture, algorithm, idea, story). Never overwrites.
• motion doctor: checks Chrome, openssl, an end-to-end build and the optional voice setup, with a fix line for each failure.
• motion --version and a VERSION file.
• Install as a Claude Code plugin: /plugin marketplace add 4lxn/motion-explainer.
• MOTION_CHROME to point at any Chrome or Chromium; Linux paths are found automatically.
• MOTION_SCALE=2 for retina-resolution motion shot PNGs.
• CI on Ubuntu and macOS; issue templates; CONTRIBUTING.md.

Changed

• Lint errors suggest the closest valid name: unknown type 'bxo'. Did you mean 'box'? (types, verbs, ids, arrow endpoints, icons, eases).
• JavaScript errors in a scene report <scene>.scene.js:<line> instead of a line in the built HTML.
• motion, motion help and --help print usage on stdout and exit 0; an unknown command is named and exits 2.
• SKILL.md finds its files through ${CLAUDE_SKILL_DIR}, so it works from any install location, and starts scenes with motion new.

Fixed

• motion open file.html 12 opened a 12x12 window; sizes must be WIDTHxHEIGHT.
• Built pages requested /favicon.ico (a 404 on most hosts).
• A scene with no steps crashed the player at boot; it now says what is missing.