ci: add pre-commit hook to detect generated base_client drift

Compares the hand-written base_client.py against the generated copy
and fails if they diverge, preventing releases with stale codegen.

Author: jdaberkow

.pre-commit-config.yaml

@@ -40,3 +40,9 @@ repos:
         language: system
         types: [python]
         exclude: "^deezer_python_gql/generated/"
+      - id: check-codegen-sync
+        name: check-codegen-sync
+        entry: scripts/check_codegen_sync.sh
+        language: script
+        always_run: true
+        pass_filenames: false

scripts/check_codegen_sync.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+# Verify that generated/base_client.py is in sync with the hand-written base_client.py.
+# The generated copy has a 2-line header ("# Generated by ariadne-codegen\n") that we skip.
+set -euo pipefail
+
+if ! diff <(tail -n +3 deezer_python_gql/generated/base_client.py) deezer_python_gql/base_client.py > /dev/null 2>&1; then
+    echo "ERROR: generated/base_client.py is out of sync with base_client.py"
+    echo "Run 'make codegen' to regenerate."
+    exit 1
+fi