feat(skills): add openclaw-persona-forge skill

Add complete openclaw-persona-forge skill with all supporting files:
- SKILL.md with community origin
- gacha.py and gacha.sh for random soul generation
- Reference docs for avatar style, boundary rules, error handling,
  identity tension, naming system, and output template

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

skills/openclaw-persona-forge/gacha.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+# 龙虾灵魂抽卡机 - 薄壳脚本
+# 实际逻辑在 gacha.py 中（Python secrets 模块保证真随机）
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+exec python3 "${SCRIPT_DIR}/gacha.py" "$@"