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.

tests/e2e/test_smoke.py

@@ -14,6 +14,7 @@ UI_ROUTES = [
     ("/ui/maintenance", "Maintenance · CalMiner", "Maintenance Schedule"),
     ("/ui/simulations", "Simulations · CalMiner", "Monte Carlo Simulations"),
     ("/ui/reporting", "Reporting · CalMiner", "Scenario KPI Summary"),
+    ("/ui/currencies", "Currencies · CalMiner", "Currency Overview"),
 ]