feat: improve skill scores for ushabti card skills

[rohan-tessl]

Hey @adamrdrew 👋

I ran your skills through tessl skill review at work and found some targeted improvements.

Here's the full before/after:

Skill	Before	After	Change
complete-card	10%	87%	+77%
create-card	10%	90%	+80%
describe-cards	10%	89%	+79%
list-cards	10%	87%	+77%
describe-ushabti	41%	75%	+34%

This PR is intentionally scoped to 5 skills to keep it reviewable — more skills can be improved in follow-ups or via automated review on future PRs.

Changes summary

complete-card, create-card, describe-cards, list-cards (10% → 87-90%)

• Added missing YAML frontmatter (name, description, user-invocable fields) — these skills were scoring 10% because tessl skill review validation requires frontmatter
• Streamlined content: consolidated redundant sections, removed duplicate code examples, tightened procedures
• Ensured descriptions use quoted string format matching the repo's existing skill conventions

describe-ushabti (41% → 75%)

• Expanded the very short content body with the core loop diagram, agent roles table, canonical state directory structure, and key principles
• Added structured description with "Use when..." clause for better discoverability
• Content drawn directly from the repo's own README and CLAUDE.md to stay accurate

Honest disclosure — I work at @tesslio where we build tooling around skills like these. Not a pitch - just saw room for improvement and wanted to contribute.

Want to self-improve your skills? Just point your agent (Claude Code, Codex, etc.) at this Tessl guide and ask it to optimize your skill. Ping me - @rohan-tessl - if you hit any snags.

Thanks in advance 🙏