feat(webui): refine output timeline and model controls (#4108)

* feat(webui): refine output timeline and composer queue

* feat(webui): add provider model picker

* fix(webui): polish model settings and heartbeat checks

* chore: keep heartbeat changes out of webui pr

* refactor(webui): isolate settings routes

* fix(providers): align minimax anthropic test

* fix(providers): keep minimax anthropic base sdk-compatible

* fix(providers): normalize anthropic base urls

webui/src/tests/code-block.test.tsx

@@ -45,6 +45,7 @@ describe("CodeBlock", () => {
     expect(screen.queryByTestId("highlighted-code")).not.toBeInTheDocument();
     expect(screen.getByText("const value = 1;")).toBeInTheDocument();
     expect(screen.getByText("ts")).toBeInTheDocument();
+    expect(screen.getByTestId("plain-code-fallback")).toHaveClass("text-foreground/90");
   });
 
   it("reads theme from context without creating per-block observers", async () => {