feat(webui): link session mentions

webui/src/tests/message-bubble.test.tsx

@@ -530,6 +530,7 @@ describe("MessageBubble", () => {
     const token = screen.getByTestId("message-session-mention-收费设计");
     expect(token).toHaveTextContent("@收费设计");
     expect(token).toHaveAttribute("title", "Session: 收费设计");
+    expect(token.closest("a")).toHaveAttribute("href", "#/chat/websocket%3Apricing");
   });
 
   it("copies completed assistant replies from the action row", async () => {

webui/src/tests/thread-composer.test.tsx

@@ -1564,9 +1564,9 @@ describe("ThreadComposer", () => {
     fireEvent.keyDown(input, { key: "Tab" });
 
     expect(input).toHaveValue("参考 @收费设计 ");
-    expect(screen.getByTestId("composer-session-mention-收费设计")).toHaveTextContent(
-      "@收费设计",
-    );
+    const mention = screen.getByTestId("composer-session-mention-收费设计");
+    expect(mention).toHaveTextContent("@收费设计");
+    expect(mention.closest("a")).toBeNull();
 
     fireEvent.click(screen.getByRole("button", { name: "Send message" }));