chore: Add pre-commit hooks for code formatting and licensing

Co-authored-by: Shangjie Chen <deanchen@google.com>
PiperOrigin-RevId: 904636630

.pre-commit-config.yaml

@@ -13,22 +13,39 @@
 # limitations under the License.
 
 repos:
--   repo: https://github.com/pre-commit/pre-commit-hooks
+  - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v4.6.0
     hooks:
-    -   id: check-added-large-files
-    -   id: check-yaml
-    -   id: end-of-file-fixer
-    -   id: trailing-whitespace
--   repo: local
+      - id: check-added-large-files
+      - id: check-yaml
+      - id: end-of-file-fixer
+      - id: trailing-whitespace
+  - repo: https://github.com/tox-dev/pyproject-fmt
+    rev: v2.5.0
     hooks:
-    -   id: isort
-        name: isort
-        entry: isort
+      - id: pyproject-fmt
+  - repo: https://github.com/PyCQA/isort
+    rev: 8.0.1
+    hooks:
+      - id: isort
+  - repo: https://github.com/google/pyink
+    rev: 25.12.0
+    hooks:
+      - id: pyink
+  - repo: local
+    hooks:
+      - id: addlicense
+        name: addlicense
+        entry: >
+          bash -c 'if command -v addlicense >/dev/null 2>&1;
+          then addlicense -c "Google LLC" -l apache "$@";
+          else echo "Warning: addlicense not installed, skipping"; fi' --
         language: system
-        types: [python]
-    -   id: pyink
-        name: pyink
-        entry: pyink --config pyproject.toml
-        language: system
-        types: [python]
+        files: \.(py|sh)$
+  - repo: https://github.com/executablebooks/mdformat
+    rev: 0.7.22
+    hooks:
+      - id: mdformat
+        files: ^(README\.md|CONTRIBUTING\.md|contributing/.*\.md)$
+        additional_dependencies:
+          - mdformat-gfm