fix: Remove 'tests' from Bandit exclude_dirs to ensure security checks cover all test files

pyproject.toml

@@ -39,6 +39,6 @@ skip_empty = true
 show_missing = true
 
 [tool.bandit]
-exclude_dirs = ["tests", "alembic", "scripts"]
+exclude_dirs = ["alembic", "scripts"]
 skips = ["B101", "B601"]  # B101: assert_used, B601: shell_injection (may be false positives)