feat: improve notification filters configuration format

- Change filters config from nested dict to simple arrays
- Update NotificationFilters model to use List[str] instead of Dict[str, str]
- Modify notification service to handle list-based filters
- Update API routes and tests for new format
- Update README with new configuration example

Before: [filters.case-insensitive] salary = 'salary'
After: [filters] case-insensitive = ['salary', 'utility']

tests/unit/test_config.py

@@ -188,7 +188,8 @@ class TestConfig:
         """Test filters configuration access."""
         custom_config = {
             "filters": {
-                "case-insensitive": {"salary": "SALARY", "bills": "BILL"},
+                "case-insensitive": ["salary", "utility"],
+                "case-sensitive": ["SpecificStore"],
                 "amount_threshold": 100.0,
             }
         }
@@ -197,5 +198,7 @@ class TestConfig:
         config._config = custom_config
 
         filters = config.filters_config
-        assert filters["case-insensitive"]["salary"] == "SALARY"
+        assert "salary" in filters["case-insensitive"]
+        assert "utility" in filters["case-insensitive"]
+        assert "SpecificStore" in filters["case-sensitive"]
         assert filters["amount_threshold"] == 100.0