feat: Add main CSS styles for the application

feat: Refactor Dashboard template to extend base layout and improve structure

feat: Enhance Parameter Input template with improved layout and feedback mechanisms

feat: Update Scenario Form template to utilize base layout and improve user experience

feat: Create base layout template for consistent styling across pages

feat: Add Consumption, Costs, Equipment, Maintenance, Production, Reporting, and Simulations templates with placeholders for future functionality

feat: Implement base header and footer partials for consistent navigation and footer across the application

templates/costs.html

@@ -0,0 +1,8 @@
+{% extends "base.html" %}
+{% block title %}Costs · CalMiner{% endblock %}
+{% block content %}
+  <section class="panel">
+    <h2>Costs</h2>
+    <p>This view will surface CAPEX and OPEX entries tied to scenarios. API wiring pending.</p>
+  </section>
+{% endblock %}