refactor: consolidate MCP integration to unified gateway

**Changes**:
- Remove individual MCP server docs (superclaude/mcp/*.md)
- Remove MCP server configs (superclaude/mcp/configs/*.json)
- Delete MCP docs component (setup/components/mcp_docs.py)
- Simplify installer (setup/core/installer.py)
- Update components for unified gateway approach

**Rationale**:
- Unified gateway (airis-mcp-gateway) provides all MCP servers
- Individual docs/configs no longer needed (managed centrally)
- Reduces maintenance burden and file count
- Simplifies installation process

**Files Removed**: 17 MCP files (docs + configs)
**Installer Changes**: Removed legacy MCP installation logic

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

setup/data/features.json

@@ -36,15 +36,6 @@
       "enabled": true,
       "required_tools": []
     },
-    "mcp_docs": {
-      "name": "mcp_docs",
-      "version": "4.1.5",
-      "description": "MCP server documentation and usage guides",
-      "category": "documentation",
-      "dependencies": ["core"],
-      "enabled": true,
-      "required_tools": []
-    },
     "agents": {
       "name": "agents",
       "version": "4.1.5",