feat: Add currency management feature with CRUD operations

- Introduced a new template for currency overview and management (`currencies.html`).
- Updated footer to include attribution to AllYouCanGET.
- Added "Currencies" link to the main navigation header.
- Implemented end-to-end tests for currency creation, update, and activation toggling.
- Created unit tests for currency API endpoints, including creation, updating, and activation toggling.
- Added a fixture to seed default currencies for testing.
- Enhanced database setup tests to ensure proper seeding and migration handling.

docs/architecture/03_context_and_scope.md

@@ -36,3 +36,22 @@ The architecture encompasses the following key areas:
 10. **Integration Points**: Interfaces for integrating with external systems and services.
 11. **Monitoring and Logging**: Systems for tracking system performance and user activity.
 12. **Maintenance and Support**: Processes for ongoing system maintenance and user support.
+
+## Diagram
+
+```mermaid
+sequenceDiagram
+    participant PM as Project Manager
+    participant DA as Data Analyst
+    participant EX as Executive
+    participant CM as CalMiner System
+
+    PM->>CM: Create and manage scenarios
+    DA->>CM: Analyze simulation results
+    EX->>CM: Review reports and dashboards
+    CM->>PM: Provide scenario planning tools
+    CM->>DA: Deliver analysis insights
+    CM->>EX: Generate high-level reports
+```
+
+This diagram illustrates the key components of the CalMiner system and their interactions with external actors.