Add comprehensive skills, agents, commands collection

- Added 44 external skills from obra/superpowers, ui-ux-pro-max-skill, claude-codex-settings
- Added 8 autonomous agents (commit-creator, pr-creator, pr-reviewer, etc.)
- Added 23 slash commands for Git/GitHub, setup, and plugin development
- Added hooks for code formatting, notifications, and validation
- Added MCP configurations for Azure, GCloud, Supabase, MongoDB, etc.
- Added awesome-openclaw-skills registry (3,002 skills referenced)
- Updated comprehensive README with full documentation

Sources:
- github.com/obra/superpowers (14 skills)
- github.com/nextlevelbuilder/ui-ux-pro-max-skill (1 skill)
- github.com/fcakyon/claude-codex-settings (29 skills, 8 agents, 23 commands)
- github.com/VoltAgent/awesome-openclaw-skills (registry)
- skills.sh (reference)
- buildwithclaude.com (reference)

skills/external/plugin-dev-mcp-integration/examples/stdio-server.json

@@ -0,0 +1,26 @@
+{
+  "_comment": "Example stdio MCP server configuration for local file system access",
+  "filesystem": {
+    "command": "npx",
+    "args": ["-y", "@modelcontextprotocol/server-filesystem", "${CLAUDE_PROJECT_DIR}"],
+    "env": {
+      "LOG_LEVEL": "info"
+    }
+  },
+  "database": {
+    "command": "${CLAUDE_PLUGIN_ROOT}/servers/db-server.js",
+    "args": ["--config", "${CLAUDE_PLUGIN_ROOT}/config/db.json"],
+    "env": {
+      "DATABASE_URL": "${DATABASE_URL}",
+      "DB_POOL_SIZE": "10"
+    }
+  },
+  "custom-tools": {
+    "command": "python",
+    "args": ["-m", "my_mcp_server", "--port", "8080"],
+    "env": {
+      "API_KEY": "${CUSTOM_API_KEY}",
+      "DEBUG": "false"
+    }
+  }
+}