feat: Add application-level settings for CSS color management

- Introduced a new table `application_setting` to store configurable application options.
- Implemented functions to manage CSS color settings, including loading, updating, and reading environment overrides.
- Added a new settings view to render and manage theme colors.
- Updated UI to include a settings page with theme color management and environment overrides display.
- Enhanced CSS styles for the settings page and sidebar navigation.
- Created unit and end-to-end tests for the new settings functionality and CSS management.

templates/partials/sidebar_nav.html

@@ -0,0 +1,88 @@
+{% set nav_groups = [
+  {
+    "label": "Dashboard",
+    "links": [
+      {"href": "/", "label": "Dashboard"},
+    ],
+  },
+  {
+    "label": "Scenarios",
+    "links": [
+      {"href": "/ui/scenarios", "label": "Overview"},
+      {"href": "/ui/parameters", "label": "Parameters"},
+      {"href": "/ui/costs", "label": "Costs"},
+      {"href": "/ui/consumption", "label": "Consumption"},
+      {"href": "/ui/production", "label": "Production"},
+      {
+        "href": "/ui/equipment",
+        "label": "Equipment",
+        "children": [
+          {"href": "/ui/maintenance", "label": "Maintenance"},
+        ],
+      },
+    ],
+  },
+  {
+    "label": "Analysis",
+    "links": [
+      {"href": "/ui/simulations", "label": "Simulations"},
+      {"href": "/ui/reporting", "label": "Reporting"},
+    ],
+  },
+  {
+    "label": "Settings",
+    "links": [
+      {
+        "href": "/ui/settings",
+        "label": "Settings",
+        "children": [
+          {"href": "/ui/currencies", "label": "Currency Management"},
+        ],
+      },
+    ],
+  },
+] %}
+
+<nav class="sidebar-nav" aria-label="Primary navigation">
+  {% set current_path = request.url.path if request else "" %}
+  {% for group in nav_groups %}
+    <div class="sidebar-section">
+      <div class="sidebar-section-label">{{ group.label }}</div>
+      <div class="sidebar-section-links">
+        {% for link in group.links %}
+          {% set href = link.href %}
+          {% if href == "/" %}
+            {% set is_active = current_path == "/" %}
+          {% else %}
+            {% set is_active = current_path.startswith(href) %}
+          {% endif %}
+          <div class="sidebar-link-block">
+            <a
+              href="{{ href }}"
+              class="sidebar-link{% if is_active %} is-active{% endif %}"
+            >
+              {{ link.label }}
+            </a>
+            {% if link.children %}
+              <div class="sidebar-sublinks">
+                {% for child in link.children %}
+                  {% if child.href == "/" %}
+                    {% set child_active = current_path == "/" %}
+                  {% else %}
+                    {% set child_active = current_path.startswith(child.href) %}
+                  {% endif %}
+                  <a
+                    href="{{ child.href }}"
+                    class="sidebar-sublink{% if child_active %} is-active{% endif %}"
+                  >
+                    {{ child.label }}
+                  </a>
+                {% endfor %}
+              </div>
+            {% endif %}
+          </div>
+        {% endfor %}
+      </div>
+    </div>
+  {% endfor %}
+</nav>