Make the command center stable and workspace-aware (#2749)

* feat(app): expand command center actions

Keep command center navigation stable by revealing only clipped rows without smooth centering. Prioritize a concise default list while making workspace, Git, pane, and creation actions searchable through the existing contribution and action-policy paths.

* test(app): search for query-only command action

Add project is intentionally absent from the unfiltered command center. Exercise the overlay flow through search before selecting it.

packages/app/e2e/provider-settings-refresh.spec.ts

@@ -156,6 +156,7 @@ test.describe("provider settings overlay stack", () => {
 
       await page.keyboard.press("ControlOrMeta+K");
       await expect(commandCenter).toBeVisible({ timeout: 10_000 });
+      await commandCenter.getByTestId("command-center-input").fill("add project");
       await commandCenter.getByText("Add project", { exact: true }).click();
       const addProject = page.getByTestId("add-project-flow");
       await expect(addProject).toBeVisible({ timeout: 10_000 });