docs(skills): Add ComposioHQ skills reference (832 API automations)

- Forked ComposioHQ/awesome-claude-skills to Gitea (Apache 2.0)
- 832 API automation skills via Rube MCP
- Includes Discord, Cloudflare, Google, and 800+ more integrations
- Also contains document-skills, theme-factory, mcp-builder

Session total: 4 skill libraries forked
- claude-skills-reference (2,375 files)
- skill-seekers-reference (2,814 files)
- claude-code-skills-reference (390 files)
- composio-skills-reference (1,138 files)

Grand total: ~6,717 files of skill knowledge

Chronicler #73

docs/skills/SKILLS-INDEX.md

@@ -580,6 +580,26 @@ skill-seekers package output/example --target qdrant
 
 **Full list:** 50 skills including terraform, i18n, QA, UI design, and more.
 
+---
+
+### composio-skills-reference (Gitea)
+**Location:** https://git.firefrostgaming.com/firefrost-gaming/composio-skills-reference  
+**Source:** Fork of [ComposioHQ/awesome-claude-skills](https://github.com/ComposioHQ/awesome-claude-skills)  
+**License:** Apache 2.0  
+**Added:** 2026-04-09 by Chronicler #73
+
+**Purpose:** 832 API automation skills via Rube MCP + document/theme/productivity skills.
+
+| Category | Count | Examples |
+|----------|-------|----------|
+| **composio-skills/** | 832 | Discord, Cloudflare, Google, Slack, Twitch, YouTube, and 800+ more APIs |
+| **document-skills/** | 4 | docx, pdf, pptx, xlsx |
+| **theme-factory/** | 10 | Pre-built themes for presentations/artifacts |
+| **mcp-builder/** | 1 | Guide for creating MCP servers |
+| **Other skills** | ~20 | internal-comms, skill-creator, webapp-testing, etc. |
+
+**Note:** Most composio-skills require Rube MCP (`https://rube.app/mcp`) for execution. These are the same patterns we use in our social-automation skills.
+
 **Contents:** 2,375 files across 20+ categories — a comprehensive AI skills library for full review.
 
 | Category | Items | Highlights |