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-hook-development/examples/validate-write.sh

@@ -0,0 +1,38 @@
+#!/bin/bash
+# Example PreToolUse hook for validating Write/Edit operations
+# This script demonstrates file write validation patterns
+
+set -euo pipefail
+
+# Read input from stdin
+input=$(cat)
+
+# Extract file path and content
+file_path=$(echo "$input" | jq -r '.tool_input.file_path // empty')
+
+# Validate path exists
+if [ -z "$file_path" ]; then
+  echo '{"continue": true}' # No path to validate
+  exit 0
+fi
+
+# Check for path traversal
+if [[ "$file_path" == *".."* ]]; then
+  echo '{"hookSpecificOutput": {"permissionDecision": "deny"}, "systemMessage": "Path traversal detected in: '"$file_path"'"}' >&2
+  exit 2
+fi
+
+# Check for system directories
+if [[ "$file_path" == /etc/* ]] || [[ "$file_path" == /sys/* ]] || [[ "$file_path" == /usr/* ]]; then
+  echo '{"hookSpecificOutput": {"permissionDecision": "deny"}, "systemMessage": "Cannot write to system directory: '"$file_path"'"}' >&2
+  exit 2
+fi
+
+# Check for sensitive files
+if [[ "$file_path" == *.env ]] || [[ "$file_path" == *secret* ]] || [[ "$file_path" == *credentials* ]]; then
+  echo '{"hookSpecificOutput": {"permissionDecision": "ask"}, "systemMessage": "Writing to potentially sensitive file: '"$file_path"'"}' >&2
+  exit 2
+fi
+
+# Approve the operation
+exit 0