feat: add unit tests to pre-commit hooks

Run unit tests locally before commit to catch issues before CI.
Addresses feedback from @drewyangdev on #1211.

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: dimitri-yatsenko

.pre-commit-config.yaml

@@ -48,3 +48,12 @@ repos:
         - types-tqdm
         - pandas-stubs
         - numpy
+- repo: local
+  hooks:
+    - id: unit-tests
+      name: unit tests
+      entry: pytest tests/unit/ -v --tb=short
+      language: system
+      pass_filenames: false
+      always_run: true
+      stages: [pre-commit]