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-plugin-structure/examples/minimal-plugin.md

@@ -0,0 +1,83 @@
+# Minimal Plugin Example
+
+A bare-bones plugin with a single command.
+
+## Directory Structure
+
+```
+hello-world/
+├── .claude-plugin/
+│   └── plugin.json
+└── commands/
+    └── hello.md
+```
+
+## File Contents
+
+### .claude-plugin/plugin.json
+
+```json
+{
+  "name": "hello-world"
+}
+```
+
+### commands/hello.md
+
+```markdown
+---
+name: hello
+description: Prints a friendly greeting message
+---
+
+# Hello Command
+
+Print a friendly greeting to the user.
+
+## Implementation
+
+Output the following message to the user:
+
+> Hello! This is a simple command from the hello-world plugin.
+>
+> Use this as a starting point for building more complex plugins.
+
+Include the current timestamp in the greeting to show the command executed successfully.
+```
+
+## Usage
+
+After installing the plugin:
+
+```
+$ claude
+> /hello
+Hello! This is a simple command from the hello-world plugin.
+
+Use this as a starting point for building more complex plugins.
+
+Executed at: 2025-01-15 14:30:22 UTC
+```
+
+## Key Points
+
+1. **Minimal manifest**: Only the required `name` field
+2. **Single command**: One markdown file in `commands/` directory
+3. **Auto-discovery**: Claude Code finds the command automatically
+4. **No dependencies**: No scripts, hooks, or external resources
+
+## When to Use This Pattern
+
+- Quick prototypes
+- Single-purpose utilities
+- Learning plugin development
+- Internal team tools with one specific function
+
+## Extending This Plugin
+
+To add more functionality:
+
+1. **Add commands**: Create more `.md` files in `commands/`
+2. **Add metadata**: Update `plugin.json` with version, description, author
+3. **Add agents**: Create `agents/` directory with agent definitions
+4. **Add hooks**: Create `hooks/hooks.json` for event handling