Add pre-commit check that model_cost.json matches model_profiles.yaml

Runs scripts/pricing/build_model_cost.py --check whenever model_cost/ or
scripts/pricing/ changes, locally and in the Pre-commit CI job.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: Louie Lu

.pre-commit-config.yaml

@@ -66,6 +66,13 @@ repos:
       entry: tools/addlicense.sh
       pass_filenames: true
       files: '\.py$'
+    - id: model-cost-in-sync
+      name: model_cost.json is generated from model_profiles.yaml
+      language: python
+      entry: python scripts/pricing/build_model_cost.py --check
+      additional_dependencies: [pyyaml]
+      pass_filenames: false
+      files: '^(model_cost/|scripts/pricing/)'
 # Add mypy hooks for both local runs and CI (manual stage)
 - repo: local
   hooks: