feat: Enhance currency handling and validation across scenarios

- Updated form template to prefill currency input with default value and added help text for clarity.
- Modified integration tests to assert more descriptive error messages for invalid currency codes.
- Introduced new tests for currency normalization and validation in various scenarios, including imports and exports.
- Added comprehensive tests for pricing calculations, ensuring defaults are respected and overrides function correctly.
- Implemented unit tests for pricing settings repository, ensuring CRUD operations and default settings are handled properly.
- Enhanced scenario pricing evaluation tests to validate currency handling and metadata defaults.
- Added simulation tests to ensure Monte Carlo runs are accurate and handle various distribution scenarios.

templates/partials/reports/scenario_actions.html

@@ -0,0 +1,14 @@
+<div class="scenario-actions">
+  <a
+    href="{{ request.url_for('reports.scenario_distribution_page', scenario_id=scenario.id) }}"
+    class="button button-secondary"
+  >
+    View Distribution
+  </a>
+  <a
+    href="{{ request.url_for('reports.scenario_distribution', scenario_id=scenario.id) }}"
+    class="button button-secondary"
+  >
+    Download JSON
+  </a>
+</div>