feat: add uxui-principles skill from uxuiprinciples/agent-skills (#441)

Co-authored-by: UX UI Principles <joselhurtado@users.noreply.github.com>

skills/uxui-principles/SKILL.md

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+---
+name: uxui-principles
+description: "Evaluate interfaces against 168 research-backed UX/UI principles, detect antipatterns, and inject UX context into AI coding sessions."
+category: design
+risk: safe
+source: community
+date_added: "2026-04-03"
+author: uxuiprinciples
+tags: [ux, ui, design, evaluation, principles, antipatterns, accessibility]
+tools: [claude, cursor, windsurf]
+---
+
+# UX/UI Principles
+
+A collection of 5 agent skills for evaluating interfaces against 168 research-backed UX/UI principles, detecting antipatterns, and injecting UX context into AI-assisted design and coding sessions.
+
+**Source:** https://github.com/uxuiprinciples/agent-skills
+
+## Skills
+
+| Skill | Purpose |
+|-------|---------|
+| `uxui-evaluator` | Evaluate interface descriptions against 168 research-backed principles |
+| `interface-auditor` | Detect UX antipatterns using the uxuiprinciples smell taxonomy |
+| `ai-interface-reviewer` | Audit AI-powered interfaces against 44 AI-era UX principles |
+| `flow-checker` | Check user flows against decision, error, and feedback principles |
+| `vibe-coding-advisor` | Inject UX context into vibe coding sessions before implementation |
+
+## When to Use
+
+- Auditing an existing interface for UX issues
+- Checking if a UI follows research-backed best practices
+- Detecting antipatterns and UX smells in designs
+- Reviewing AI-powered interfaces for trust, transparency, and safety
+- Getting UX guidance before or during implementation
+
+## How It Works
+
+1. Install any skill from the collection
+2. Describe the interface, screen, or flow you want to evaluate
+3. The skill evaluates against the relevant principles and returns structured findings with severity levels and remediation steps
+4. Optionally connect to the uxuiprinciples.com API for enriched output with full citations
+
+## Install
+
+```
+npx skills add uxuiprinciples/agent-skills
+```