重构: 后端 df-ai/commands 拆分+df-nodes/workflow 改造+P0 bug 修复

- df-ai: context 历史中毒三档自愈 sanitize_messages(AC3)+anthropic_compat tool_use_id None 跳过(AC1/AC2)+删 router/stream 死码
- df-core: events 加 select_type+decisions 多选审批契约(F-260615-01)
- df-execute: shell run_command 工具复用(F-260615-05)
- df-nodes: human_node 多选校验+2 端到端测(F-01)+取消跳 set_failed(B-03b-R1/R2/R8)
- df-workflow: executor/dag/state cancel 闭环(B-06/07/03a/b)+provider approve options(R-PD-5)
- df-storage: find_path_conflict 抽公共(R-PD-11)+COLS 常量断言
- df-ideas: 删 IdeaPromoter/PromotionPolicy 死码(R-PD-14)
- src-tauri/commands/ai: secret keyring 迁移(FR-S1/R-PD-4)+GeneratingGuard RAII+disarm(B-09/26)+newConversation 软复位(B-10)+stream 心跳/stop select/空回复判错(B-02/04/05/15)+run_command(F-05)+mask audit(AR-3)
- src-tauri/commands/{project,task,workflow,mod,lib,state}: task detail IPC(F-02)+approve decisions+task list 联动(B-29)
- Cargo.lock+Cargo.toml 依赖同步

crates/df-ai/src/router.rs

@@ -1,51 +0,0 @@
-//! 模型路由 — 根据任务类型选择最优模型
-
-use serde::{Deserialize, Serialize};
-
-/// 任务类型
-#[derive(Debug, Clone, Serialize, Deserialize)]
-#[serde(rename_all = "snake_case")]
-pub enum TaskType {
-    /// 代码生成
-    CodeGeneration,
-    /// 代码审查
-    CodeReview,
-    /// 文档生成
-    Documentation,
-    /// 分析推理
-    Analysis,
-    /// 摘要总结
-    Summarization,
-    /// 通用对话
-    Chat,
-}
-
-/// 模型路由器
-///
-/// 根据任务类型、成本、延迟等选择最优模型
-pub struct ModelRouter {
-    /// 默认模型
-    default_model: String,
-}
-
-impl ModelRouter {
-    /// 创建路由器
-    pub fn new(default_model: &str) -> Self {
-        Self {
-            default_model: default_model.to_string(),
-        }
-    }
-
-    /// 根据任务类型路由到合适的模型
-    pub fn route(&self, task_type: &TaskType) -> String {
-        // TODO: 实现基于规则的模型路由
-        match task_type {
-            TaskType::CodeGeneration => self.default_model.clone(),
-            TaskType::CodeReview => self.default_model.clone(),
-            TaskType::Documentation => self.default_model.clone(),
-            TaskType::Analysis => self.default_model.clone(),
-            TaskType::Summarization => self.default_model.clone(),
-            TaskType::Chat => self.default_model.clone(),
-        }
-    }
-}