fix(cli): clarify completion cache timeout message after openclaw update

When the post-update completion cache refresh times out (slow disk,
large bundled plugin tree, Docker overlayfs), the user previously saw
the opaque 'Completion cache update failed: Error: spawnSync
/usr/bin/node ETIMEDOUT'. Detect ETIMEDOUT specifically, surface
'timed out after 30s', and append a manual refresh hint pointing at
'openclaw completion --write-state' so users know it's non-fatal and
how to recover.

Fixes #72842

src/cli/update-cli.test.ts

@@ -549,6 +549,31 @@ describe("update-cli", () => {
     );
   });
 
+  it("logs friendly hint with manual refresh command when completion cache write times out", async () => {
+    const root = createCaseDir("openclaw-completion-timeout-msg");
+    pathExists.mockResolvedValue(true);
+    const timeoutErr = Object.assign(new Error("spawnSync /usr/bin/node ETIMEDOUT"), {
+      code: "ETIMEDOUT",
+    });
+    vi.mocked(spawnSync).mockReturnValueOnce({
+      pid: 0,
+      output: [],
+      stdout: "",
+      stderr: "",
+      status: null,
+      signal: null,
+      error: timeoutErr,
+    });
+    vi.mocked(runtimeCapture.log).mockClear();
+
+    await updateCliShared.tryWriteCompletionCache(root, false);
+
+    const logs = vi.mocked(runtimeCapture.log).mock.calls.map((call) => String(call[0]));
+    expect(logs.some((line) => line.includes("timed out after 30s"))).toBe(true);
+    expect(logs.some((line) => line.includes("openclaw completion --write-state"))).toBe(true);
+    expect(logs.some((line) => line.includes("Error: spawnSync"))).toBe(false);
+  });
+
   it("respawns into the updated package root before running post-update tasks", async () => {
     const { entrypoints } = setupUpdatedRootRefresh();