fix(growth): Evolution Engine 审计修复 — 7项全部完成

HIGH-1: 提取共享 json_utils.rs，skill_generator/workflow_composer 去重
HIGH-2: FeedbackCollector Vec→HashMap，消除 unwrap() panic 风险
HIGH-3: ProfileUpdater 改为 collect_updates() 返回字段列表，
        growth.rs 直接 async 调用 update_field()，不再用 no-op 闭包
MEDIUM-1: EvolutionMiddleware 注入后自动 drain，防止重复注入
MEDIUM-2: PatternAggregator tools 提取改为直接收集 context 值
MEDIUM-3: evolution_engine.rs 移除 4 个未使用 imports
MEDIUM-4: workflow_composer parse_response pattern 参数加下划线
MEDIUM-7: SkillCandidate 添加 version 字段（默认=1）

测试: zclaw-growth 128 tests, zclaw-runtime 86 tests, workspace 0 failures

crates/zclaw-growth/src/evolution_engine.rs

@@ -9,8 +9,7 @@ use std::sync::Arc;
 
 use crate::experience_store::ExperienceStore;
 use crate::feedback_collector::{
-    EvolutionArtifact, FeedbackCollector, FeedbackEntry, FeedbackSignal, RecommendedAction,
-    Sentiment, TrustUpdate,
+    FeedbackCollector, FeedbackEntry, TrustUpdate,
 };
 use crate::pattern_aggregator::{AggregatedPattern, PatternAggregator};
 use crate::quality_gate::{QualityGate, QualityReport};