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/masking.py

@@ -3,7 +3,7 @@ Module for masking sensitive information in configuration values
 """
 
 
-def mask_sensitive_value(value):
+def mask_sensitive_value(value: str | None) -> str | None:
     """
     Masks sensitive values like API keys in logs and output
     """