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.

docs/architecture/07_deployment_view.md

@@ -15,7 +15,12 @@ The CalMiner application is deployed using a multi-tier architecture consisting
 1. **Client Layer**: This layer consists of web browsers that interact with the application through a user interface rendered by Jinja2 templates and enhanced with JavaScript (Chart.js for dashboards).
 2. **Web Application Layer**: This layer hosts the FastAPI application, which handles API requests, business logic, and serves HTML templates. It communicates with the database layer for data persistence.
 3. **Database Layer**: This layer consists of a PostgreSQL database that stores all application data, including scenarios, parameters, costs, consumption, production outputs, equipment, maintenance logs, and simulation results.
-4. **Caching Layer**: This layer uses Redis to cache frequently accessed data and improve application performance.
+
+```mermaid
+graph TD
+    A[Client Layer<br/>(Web Browsers)] --> B[Web Application Layer<br/>(FastAPI)]
+    B --> C[Database Layer<br/>(PostgreSQL)]
+```
 
 ## Infrastructure Components
 
@@ -29,6 +34,16 @@ The infrastructure components for the application include:
 - **CI/CD Pipeline**: Automated pipelines (Gitea Actions) run tests, build/push Docker images, and trigger deployments.
 - **Cloud Infrastructure (optional)**: The application can be deployed on cloud platforms.
 
+```mermaid
+graph TD
+    A[Web Server] --> B[Database Server]
+    A --> C[Static File Server]
+    A --> D[Reverse Proxy]
+    A --> E[Containerization]
+    A --> F[CI/CD Pipeline]
+    A --> G[Cloud Infrastructure]
+```
+
 ## Environments
 
 The application can be deployed in multiple environments to support development, testing, and production: