feat: 7-61 Yuxi reference — extensions panel, KB detail, manifest split, event router, dashboard

Batch B: settings popover 新增"扩展"tab，按知识库/Skills/MCP/Agent工具分面板
Batch C: knowledge-rag popover 新增"资料源管理/检索测试/检索参数"三tab
Batch A: manifest.rs 按能力域拆为 10 个分组函数（context/doc/knowledge_rag/block/page/mindmap/office/onlyoffice/artifact）
Batch D: 新增 agent-stream-event-router.js 共享模块（事件状态机 + SSE 帧解析）
Batch E: settings popover 新增"仪表盘"tab — 知识库文件数/Skills数量/MCP连接状态/Agent run次数

836/838 Rust 测试通过（仅 2 个预存失败）

rust/crates/mnote-web/src/routes/web_shell.rs

@@ -2456,6 +2456,15 @@ pub async fn sidebar_tree_runtime_asset() -> Response {
         .unwrap_or_else(|_| Response::new(Body::empty()))
 }
 
+pub async fn agent_stream_event_router_asset() -> Response {
+    const JS: &str = include_str!("../../browser/agent-stream-event-router.js");
+    Response::builder()
+        .header("content-type", "application/javascript; charset=utf-8")
+        .header("cache-control", "public, max-age=3600")
+        .body(Body::from(JS))
+        .expect("agent-stream-event-router.js")
+}
+
 pub async fn sidebar_page_ai_runtime_asset() -> Response {
     const JS: &str = include_str!("../../browser/sidebar-page-ai-runtime.js");
     Response::builder()