Update extension examples (#16274)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

packages/cli/src/commands/extensions/examples/hooks/gemini-extension.json

@@ -0,0 +1,4 @@
+{
+  "name": "hooks-example",
+  "version": "1.0.0"
+}

packages/cli/src/commands/extensions/examples/hooks/hooks/hooks.json

@@ -0,0 +1,14 @@
+{
+  "hooks": {
+    "SessionStart": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "node ${extensionPath}/scripts/on-start.js"
+          }
+        ]
+      }
+    ]
+  }
+}

packages/cli/src/commands/extensions/examples/hooks/scripts/on-start.js

@@ -0,0 +1,8 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+console.log(
+  'Session Started! This is running from a script in the hooks-example extension.',
+);