feat: add scenarios list page with metrics and quick actions

- Introduced a new template for listing scenarios associated with a project.
- Added metrics for total, active, draft, and archived scenarios.
- Implemented quick actions for creating new scenarios and reviewing project overview.
- Enhanced navigation with breadcrumbs for better user experience.

refactor: update Opex and Profitability templates for consistency

- Changed titles and button labels for clarity in Opex and Profitability templates.
- Updated form IDs and action URLs for better alignment with new naming conventions.
- Improved navigation links to include scenario and project overviews.

test: add integration tests for Opex calculations

- Created new tests for Opex calculation HTML and JSON flows.
- Validated successful calculations and ensured correct data persistence.
- Implemented tests for currency mismatch and unsupported frequency scenarios.

test: enhance project and scenario route tests

- Added tests to verify scenario list rendering and calculator shortcuts.
- Ensured scenario detail pages link back to the portfolio correctly.
- Validated project detail pages show associated scenarios accurately.

templates/partials/base_header.html

@@ -6,9 +6,5 @@
       <span class="brand-subtitle">Mining Planner</span>
     </div>
   </a>
-  <div class="sidebar-nav-controls">
-    <button id="nav-prev" class="nav-chevron nav-chevron-prev" aria-label="Previous page">&larr;</button>
-    <button id="nav-next" class="nav-chevron nav-chevron-next" aria-label="Next page">&rarr;</button>
-  </div>
   {% include "partials/sidebar_nav.html" %}
 </div>