feat: Add Processing Opex functionality

- Introduced OpexValidationError for handling validation errors in processing opex calculations.
- Implemented ProjectProcessingOpexRepository and ScenarioProcessingOpexRepository for managing project and scenario-level processing opex snapshots.
- Enhanced UnitOfWork to include repositories for processing opex.
- Updated sidebar navigation and scenario detail templates to include links to the new Processing Opex Planner.
- Created a new template for the Processing Opex Planner with form handling for input components and parameters.
- Developed integration tests for processing opex calculations, covering HTML and JSON flows, including validation for currency mismatches and unsupported frequencies.
- Added unit tests for the calculation logic, ensuring correct handling of various scenarios and edge cases.

templates/scenarios/detail.html

@@ -14,9 +14,11 @@
 
   <header class="page-header">
     {% set profitability_href = url_for('calculations.profitability_form') %}
+    {% set processing_opex_href = url_for('calculations.processing_opex_form') %}
     {% set capex_href = url_for('calculations.capex_form') %}
     {% if project and scenario %}
       {% set profitability_href = profitability_href ~ '?project_id=' ~ project.id ~ '&scenario_id=' ~ scenario.id %}
+      {% set processing_opex_href = processing_opex_href ~ '?project_id=' ~ project.id ~ '&scenario_id=' ~ scenario.id %}
       {% set capex_href = capex_href ~ '?project_id=' ~ project.id ~ '&scenario_id=' ~ scenario.id %}
     {% endif %}
     <div>
@@ -26,6 +28,7 @@
     <div class="header-actions">
       <a class="btn" href="{{ url_for('projects.view_project', project_id=project.id) }}">Back to Project</a>
       <a class="btn" href="{{ profitability_href }}">Profitability Calculator</a>
+      <a class="btn" href="{{ processing_opex_href }}">Processing Opex Planner</a>
       <a class="btn" href="{{ capex_href }}">Initial Capex Planner</a>
       <a class="btn primary" href="{{ url_for('scenarios.edit_scenario_form', scenario_id=scenario.id) }}">Edit Scenario</a>
     </div>