Ship Godot UI workflow skill and installer (3.9.0)

[cdowin]

Closes #127.

Native UI changes now have a Godot-specific skill that turns an approved wireframe into an explicit component contract, a bounded scene hierarchy, and native state/capture proof. It connects optional general UI skills without depending on agentic-sdlc.

install-skills installs the bundled godot-ui resources for Codex or Claude. It supports currentness checks and diffs and refuses collisions and unsafe destinations before writing. The skill is included in the wheel.

Validation

• Focused installer and boundary tests: 13 passed, 32 subtests before the directory-symlink review fix; follow-up proof recorded below.
• Native Codex discovery changed from 13 skills with no Godot skill to an enabled user godot-ui skill, errors empty.
• A fresh read-only Codex task implicitly selected and read the installed skill. Given a minimal tablet Bonds scene, it identified missing region allocation and scroll boundaries and proposed native evidence without claiming unrun visual proof.
• Built wheel contains SKILL.md and agents/openai.yaml.
• Full precommit passed: 305 tests, 167 subtests. After the review fix, focused installer/boundary proof passed: 14 tests, 32 subtests.

Wiki: Verb-reference

godot-devkit install-skills [--runtime codex|claude] [--dest ROOT] [--check] [--diff] [--force]
Installs godot-ui under the selected skills root. Defaults to .agents/skills for Codex and .claude/skills for Claude in the current repository. Explicit destinations permit user scope. --check is read-only and returns 1 for missing or outdated files. --diff previews changes without writing. Differing regular files require --force; symlinks below the chosen root are refused. The explicitly chosen root may itself be a symlink.

Release notes

3.9.0 minor: add a bundled Godot UI design/verification skill and an install-skills CLI verb.
Upgrade: no required edit; opt in with godot-devkit install-skills --runtime codex or --runtime claude and route native UI work through godot-ui in project instructions.