fix(growth): 二次审计修复 — 6项 CRITICAL/HIGH/MEDIUM 全部修复

CRITICAL-1/2: json_utils 花括号匹配改为括号平衡算法
  - 处理字符串字面量中的花括号和转义引号
  - 新增 5 个测试（平衡匹配、字符串内花括号、转义引号、extract_string_array）

HIGH-4: EvolutionMiddleware 只取第一个事件(remove(0))，不丢弃后续
HIGH-5: EvolutionMiddleware 先 read() 判空再 write()，减少锁竞争
HIGH-7: from_experience_store 使用传入 store 的 viking 实例（不再忽略参数）
  - ExperienceStore 新增 viking() getter

MEDIUM-9: skill_generator + workflow_composer JSON 数组解析去重
  - 新增 json_utils::extract_string_array() 共享函数
MEDIUM-14: EvolutionMiddleware 注入文本去除多余缩进空格

测试: zclaw-growth 133 tests, zclaw-runtime 87 tests, workspace 0 failures

crates/zclaw-growth/src/experience_store.rs

@@ -109,6 +109,11 @@ impl ExperienceStore {
         Self { viking }
     }
 
+    /// Get a reference to the underlying VikingAdapter.
+    pub fn viking(&self) -> &Arc<VikingAdapter> {
+        &self.viking
+    }
+
     /// Store (or overwrite) an experience. The URI is derived from
     /// `agent_id + pain_pattern`, ensuring one experience per pattern.
     pub async fn store_experience(&self, exp: &Experience) -> zclaw_types::Result<()> {