feat(FN-1889): add executor project model UI to settings modal

- Add execution model selection dropdown to project settings modal
- Include execution lane in project model lanes filter for better context
- Add test coverage for execution model in project settings
- Include changeset for @gsxdsm/fusion package

packages/dashboard/app/components/SettingsModal.tsx

@@ -1026,10 +1026,10 @@ export function SettingsModal({
         const presetOptions = presets.map((preset) => ({ id: preset.id, name: preset.name }));
         const inUsePresetIds = new Set(Object.values(form.defaultPresetBySize || {}).filter(Boolean));
 
-        // Filter model lanes to show in project scope (planning, validator, summarization)
-        // Default and execution lanes are global-only
+        // Filter model lanes to show in project scope (execution, planning, validator, summarization)
+        // Default lane is global-only
         const projectModelLanes = MODEL_LANES.filter(
-          (lane) => lane.laneId === "planning" || lane.laneId === "validator" || lane.laneId === "summarization",
+          (lane) => lane.laneId === "execution" || lane.laneId === "planning" || lane.laneId === "validator" || lane.laneId === "summarization",
         );
 
         return (

packages/dashboard/app/components/__tests__/SettingsModal.test.tsx

@@ -923,6 +923,29 @@ describe("SettingsModal", () => {
     expect(projectPayload.validatorModelId).toBe("gpt-4o");
   });
 
+  it("saving in Project Models section updates project settings with execution model", async () => {
+    const user = userEvent.setup();
+    render(<SettingsModal onClose={onClose} addToast={addToast} />);
+    await waitFor(() => expect(fetchSettings).toHaveBeenCalled());
+
+    // Click on "Project Models" (project-scoped models section)
+    fireEvent.click(screen.getByText("Project Models"));
+    await waitFor(() => expect(fetchModels).toHaveBeenCalled());
+
+    // Select execution model
+    const executionTrigger = screen.getByLabelText("Execution Model");
+    await user.click(executionTrigger);
+    await user.click(screen.getByText("Claude Sonnet 4.5"));
+
+    fireEvent.click(screen.getByText("Save"));
+
+    // Verify execution settings are saved as project settings
+    await waitFor(() => expect(updateSettings).toHaveBeenCalledTimes(1));
+    const projectPayload = (updateSettings as ReturnType<typeof vi.fn>).mock.calls[0][0];
+    expect(projectPayload.executionProvider).toBe("anthropic");
+    expect(projectPayload.executionModelId).toBe("claude-sonnet-4-5");
+  });
+
   it("saving in Project Models section updates planning and validator fallback models", async () => {
     const user = userEvent.setup();
     render(<SettingsModal onClose={onClose} addToast={addToast} />);