feat: Initial agent-skills repo — 4 adapted skills for Mosaic Stack

Skills included:
- pr-reviewer: Adapted for Gitea/GitHub via platform-aware scripts
  (dropped fetch_pr_data.py and add_inline_comment.py, kept generate_review_files.py)
- code-review-excellence: Methodology and checklists (React, TS, Python, etc.)
- vercel-react-best-practices: 57 rules for React/Next.js performance
- tailwind-design-system: Tailwind CSS v4 patterns, CVA, design tokens

New shell scripts added to ~/.claude/scripts/git/:
- pr-diff.sh: Get PR diff (GitHub gh / Gitea API)
- pr-metadata.sh: Get PR metadata as normalized JSON

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

skills/code-review-excellence/assets/pr-review-template.md

@@ -0,0 +1,114 @@
+# PR Review Template
+
+Copy and use this template for your code reviews.
+
+---
+
+## Summary
+
+[Brief overview of what was reviewed - 1-2 sentences]
+
+**PR Size:** [Small/Medium/Large] (~X lines)
+**Review Time:** [X minutes]
+
+## Strengths
+
+- [What was done well]
+- [Good patterns or approaches used]
+- [Improvements from previous code]
+
+## Required Changes
+
+🔴 **[blocking]** [Issue description]
+> [Code location or example]
+> [Suggested fix or explanation]
+
+🔴 **[blocking]** [Issue description]
+> [Details]
+
+## Important Suggestions
+
+🟡 **[important]** [Issue description]
+> [Why this matters]
+> [Suggested approach]
+
+## Minor Suggestions
+
+🟢 **[nit]** [Minor improvement suggestion]
+
+💡 **[suggestion]** [Alternative approach to consider]
+
+## Questions
+
+❓ [Clarification needed about X]
+
+❓ [Question about design decision Y]
+
+## Security Considerations
+
+- [ ] No hardcoded secrets
+- [ ] Input validation present
+- [ ] Authorization checks in place
+- [ ] No SQL/XSS injection risks
+
+## Test Coverage
+
+- [ ] Unit tests added/updated
+- [ ] Edge cases covered
+- [ ] Error cases tested
+
+## Verdict
+
+**[ ] ✅ Approve** - Ready to merge
+**[ ] 💬 Comment** - Minor suggestions, can merge
+**[ ] 🔄 Request Changes** - Must address blocking issues
+
+---
+
+## Quick Copy Templates
+
+### Blocking Issue
+```
+🔴 **[blocking]** [Title]
+
+[Description of the issue]
+
+**Location:** `file.ts:123`
+
+**Suggested fix:**
+\`\`\`typescript
+// Your suggested code
+\`\`\`
+```
+
+### Important Suggestion
+```
+🟡 **[important]** [Title]
+
+[Why this is important]
+
+**Consider:**
+- Option A: [description]
+- Option B: [description]
+```
+
+### Minor Suggestion
+```
+🟢 **[nit]** [Suggestion]
+
+Not blocking, but consider [improvement].
+```
+
+### Praise
+```
+🎉 **[praise]** Great work on [specific thing]!
+
+[Why this is good]
+```
+
+### Question
+```
+❓ **[question]** [Your question]
+
+I'm curious about the decision to [X]. Could you explain [Y]?
+```