feat: add strict mypy type-checking for app/utils/ module

- Add [[tool.mypy.overrides]] section for app/utils/** with disallow_untyped_defs=true
- Add type annotations to all functions in app/utils/ (12 files)
- Fix type annotations in app/config.py and app/database.py (imported by utils)
- All 85 source files now pass mypy type checking

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

app/utils/config_validator/validators.py

@@ -9,7 +9,7 @@ from app.config import settings
 logger = logging.getLogger(__name__)
 
 
-def validate_email_config():
+def validate_email_config() -> list[str]:
     """Validates email configuration settings"""
     issues = []
 
@@ -36,7 +36,7 @@ def validate_email_config():
     return issues
 
 
-def validate_auth_config():
+def validate_auth_config() -> list[str]:
     """Validates authentication configuration settings"""
     issues = []
 
@@ -69,7 +69,7 @@ def validate_auth_config():
     return issues
 
 
-def validate_storage_configs():
+def validate_storage_configs() -> dict[str, list[str]]:
     """Validates configuration for all storage providers"""
     issues = {}
 
@@ -178,7 +178,7 @@ def validate_storage_configs():
     return issues
 
 
-def validate_notification_config():
+def validate_notification_config() -> list[str]:
     """Check notification configuration"""
     issues = []
 
@@ -210,7 +210,7 @@ def validate_notification_config():
     return issues
 
 
-def check_all_configs():
+def check_all_configs() -> dict[str, list[str] | dict[str, list[str]]]:
     """Run all configuration validations and log results"""
     from app.utils.config_validator.settings_display import dump_all_settings