feat: Add application-level settings for CSS color management

- Introduced a new table `application_setting` to store configurable application options.
- Implemented functions to manage CSS color settings, including loading, updating, and reading environment overrides.
- Added a new settings view to render and manage theme colors.
- Updated UI to include a settings page with theme color management and environment overrides display.
- Enhanced CSS styles for the settings page and sidebar navigation.
- Created unit and end-to-end tests for the new settings functionality and CSS management.

tests/unit/conftest.py

@@ -34,6 +34,7 @@ TestingSessionLocal = sessionmaker(
 def setup_database() -> Generator[None, None, None]:
     # Ensure all model metadata is registered before creating tables
     from models import (
+        application_setting,
         capex,
         consumption,
         distribution,
@@ -52,6 +53,7 @@ def setup_database() -> Generator[None, None, None]:
         distribution,
         equipment,
         maintenance,
+        application_setting,
         opex,
         parameters,
         production_output,