fix: remove the conversation runtime override dot

Keep the Runtime icon and label clear after a conversation-specific selection. Preserve override details and the reset action inside the picker, with regression coverage and bilingual release notes.

Release note: 移除会话 Runtime 按钮图标与名称之间的圆点，保留菜单内的单独选择提示与恢复项目默认操作。

src/renderer/src/App.test.tsx

@@ -10407,6 +10407,12 @@ describe("App", () => {
       }),
     );
     expect(api.settings.updateRuntime).not.toHaveBeenCalled();
+    expect(runtimeButton).not.toHaveClass("model-button--override");
+    fireEvent.click(runtimeButton);
+    expect(screen.getByText("本会话单独选择")).toBeInTheDocument();
+    expect(
+      screen.getByRole("menuitem", { name: "恢复为项目默认" }),
+    ).toBeInTheDocument();
     expect(
       screen.queryByRole("heading", { name: "设置中心" }),
     ).not.toBeInTheDocument();

src/renderer/src/App.tsx

@@ -10184,7 +10184,7 @@ function App(): React.JSX.Element {
                                   <button
                                     aria-expanded={runtimeMenuOpen}
                                     aria-haspopup="menu"
-                                    className={`model-button${activeConversation?.runtimeSelection ? " model-button--override" : ""}`}
+                                    className="model-button"
                                     disabled={isRunning || runtimeSwitching}
                                     onClick={() => {
                                       setComposerOptionsOpen(false);

src/renderer/src/WorkspacePrimitives.test.tsx

@@ -469,6 +469,10 @@ describe('WorkspacePrimitives', () => {
       /\.composer__options\[hidden\]\s*\{[^}]*display:\s*none;/u
     )
   })
+  it('does not insert an override dot before the Runtime label', () => {
+    expect(stylesheet).not.toContain('model-button--override')
+    expect(stylesheet).not.toMatch(/\.model-button__label::before/u)
+  })
 
   it('keeps shared controls keyboard and pointer accessible at narrow widths', () => {
     expect(stylesheet).toMatch(

src/renderer/src/styles.css

@@ -8084,16 +8084,6 @@ button > svg {
   font-size: var(--font-caption);
 }
 
-.model-button--override .model-button__label::before {
-  content: "";
-  display: inline-block;
-  width: 6px;
-  height: 6px;
-  margin-right: 6px;
-  border-radius: 50%;
-  background: var(--accent);
-  vertical-align: middle;
-}
 
 .send-button {
   display: grid;