feat: add minimal pre-commit infrastructure

- Add pre-commit configuration with essential checks only
- Check YAML, TOML, JSON syntax
- Check for merge conflicts and large files
- Enforce LF line endings (fix 2 test files with CRLF)
- Add debug statement detection
- Integrate ruff for Python formatting and linting
- Add GitHub workflow for pre-commit CI
- No unnecessary Python code changes

Author: dguido

.github/workflows/pre-commit.yml

@@ -0,0 +1,16 @@
+name: Pre-commit
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  pre-commit:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.12'
+      - uses: pre-commit/action@v3.0.1

.pre-commit-config.yaml

@@ -0,0 +1,53 @@
+# Pre-commit hooks for Buttercup CRS
+# See https://pre-commit.com for more information
+
+repos:
+  # Standard file fixes
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v5.0.0
+    hooks:
+      - id: check-yaml
+        args: [--allow-multiple-documents]
+        exclude: 'deployment/k8s/.*\.(yaml|yml)$'
+      - id: check-added-large-files
+        args: [--maxkb=1000]
+      - id: check-merge-conflict
+      - id: mixed-line-ending
+        args: [--fix=lf]
+      - id: check-toml
+      - id: check-json
+      - id: debug-statements
+
+  # Ruff - Python linting and formatting
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.12.0
+    hooks:
+      # Run the formatter first
+      - id: ruff-format
+        types_or: [python, pyi]
+
+      # Then run the linter with auto-fix
+      - id: ruff
+        types_or: [python, pyi]
+        args: [--fix, --exit-non-zero-on-fix]
+
+# Global exclusions for files that should never be checked
+exclude: |
+  (?x)^(
+    external/.*|
+    .*\.pb\.py|
+    .*_pb2\.py|
+    .*_pb2_grpc\.py|
+    .*/\.venv/.*|
+    .*/\.mypy_cache/.*|
+    .*/\.ruff_cache/.*|
+    .*/\.pytest_cache/.*|
+    __pycache__/.*|
+    .*\.egg-info/.*
+  )$
+
+# Configuration
+fail_fast: false
+ci:
+  autofix_prs: true
+  autoupdate_schedule: weekly