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/scenarios/opex.html

@@ -1,5 +1,5 @@
 {% extends "base.html" %}
-{% block title %}Processing Opex Planner · CalMiner{% endblock %}
+{% block title %}Opex Planner · CalMiner{% endblock %}
 
 {% block content %}
   <nav class="breadcrumb">
@@ -10,19 +10,26 @@
     {% if scenario %}
       <a href="{{ url_for('scenarios.view_scenario', scenario_id=scenario.id) }}">{{ scenario.name }}</a>
     {% endif %}
-    <span aria-current="page">Processing Opex Planner</span>
+    <span aria-current="page">Opex Planner</span>
   </nav>
 
   <header class="page-header">
     <div>
-      <h1>Processing Opex Planner</h1>
+      <h1>Opex Planner</h1>
       <p class="text-muted">Capture recurring operational costs and review annual totals with escalation assumptions.</p>
     </div>
     <div class="header-actions">
-      {% if cancel_url %}
-        <a class="btn" href="{{ cancel_url }}">Cancel</a>
+      {% if scenario_url %}
+        <a class="btn" href="{{ scenario_url }}">Scenario Overview</a>
+      {% elif project_url %}
+        <a class="btn" href="{{ project_url }}">Project Overview</a>
+      {% elif cancel_url %}
+        <a class="btn" href="{{ cancel_url }}">Back</a>
       {% endif %}
-      <button class="btn primary" type="submit" form="processing-opex-form">Save &amp; Calculate</button>
+      {% if scenario_portfolio_url %}
+        <a class="btn" href="{{ scenario_portfolio_url }}">Scenario Portfolio</a>
+      {% endif %}
+      <button class="btn primary" type="submit" form="opex-form">Save &amp; Calculate</button>
     </div>
   </header>
 
@@ -47,7 +54,7 @@
     </div>
   {% endif %}
 
-  <form id="processing-opex-form" class="form scenario-form" method="post" action="{{ form_action }}">
+  <form id="opex-form" class="form scenario-form" method="post" action="{{ form_action }}">
     <input type="hidden" name="csrf_token" value="{{ csrf_token or '' }}" />
     <input type="hidden" name="options[persist]" value="{{ '1' if options and options.persist else '' }}" />