ci: add basic presubmits (#22)

* ci: add basic presubmits

* Update presubmit-tests.yml

Author: twishabansal

.github/workflows/presubmit-tests.yml

@@ -0,0 +1,31 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+name: Presubmit Tests
+
+on:
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  run-presubmit-tests:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+
+      - name: Install Gemini CLI
+        run: npm install @google/gemini-cli
+
+      - name: Install Extension
+        run: npx gemini extensions install --path=.