docs: 更新 README feature 表 + 升级指南 + 示例注释 + roadmap 同步

- README 添加 feature 组合表 + 模块级 features 清单 + 升级指南
- 18 个 example 顶部添加 Required features 注释
- roadmap.md 和 roadmap-v0.3.2.md 同步 Phase 26-27 完成状态
- cargo fmt 全量格式化（修复预存格式问题，CI format job 可通过）

src/agent/runtime.rs

@@ -16,9 +16,9 @@ use std::sync::Arc;
 use std::time::Duration;
 
 use crate::agent::summary::SummaryConfig;
+use crate::llm::LlmProvider;
 use crate::llm::compact::CompactConfig;
 use crate::llm::hooks::HookExecutor;
-use crate::llm::LlmProvider;
 use crate::memory::retriever::MemoryRetriever;
 use crate::memory::store::MemoryStore;
 use crate::tools::ToolRegistry;