Refactor test cases for improved readability and consistency

- Updated test functions in various test files to enhance code clarity by formatting long lines and improving indentation.
- Adjusted assertions to use multi-line formatting for better readability.
- Added new test cases for theme settings API to ensure proper functionality.
- Ensured consistent use of line breaks and spacing across test files for uniformity.

templates/theme_settings.html

@@ -0,0 +1,125 @@
+{% extends "base.html" %} {% block title %}Theme Settings · CalMiner{% endblock
+%} {% block content %}
+<section class="page-header">
+  <div>
+    <h1>Theme Settings</h1>
+    <p class="page-subtitle">
+      Adjust CalMiner theme colors and preview changes instantly.
+    </p>
+  </div>
+</section>
+
+<section class="panel" id="theme-settings" data-api="/api/settings/css">
+  <header class="panel-header">
+    <div>
+      <h2>Theme Colors</h2>
+      <p class="chart-subtitle">
+        Update global CSS variables to customize CalMiner&apos;s appearance.
+      </p>
+    </div>
+  </header>
+  <form id="theme-settings-form" class="form-grid color-form-grid" novalidate>
+    {% for key, value in css_variables.items() %} {% set env_meta =
+    css_env_override_meta.get(key) %}
+    <label
+      class="color-form-field{% if env_meta %} is-env-override{% endif %}"
+      data-variable="{{ key }}"
+    >
+      <span class="color-field-header">
+        <span class="color-field-name">{{ key }}</span>
+        <span class="color-field-default"
+          >Default: {{ css_defaults[key] }}</span
+        >
+      </span>
+      <span class="color-field-helper" id="color-helper-{{ loop.index }}"
+        >Accepts hex, rgb(a), or hsl(a) values.</span
+      >
+      {% if env_meta %}
+      <span class="color-env-flag"
+        >Managed via {{ env_meta.env_var }} (read-only)</span
+      >
+      {% endif %}
+      <span class="color-input-row">
+        <input
+          type="text"
+          name="{{ key }}"
+          class="color-value-input"
+          value="{{ value }}"
+          autocomplete="off"
+          aria-describedby="color-helper-{{ loop.index }}"
+          {%
+          if
+          env_meta
+          %}disabled
+          aria-disabled="true"
+          data-env-override="true"
+          {%
+          endif
+          %}
+        />
+        <span
+          class="color-preview"
+          aria-hidden="true"
+          style="background: {{ value }}"
+        ></span>
+      </span>
+    </label>
+    {% endfor %}
+
+    <div class="button-row">
+      <button type="submit" class="btn primary">Save Theme</button>
+      <button type="button" class="btn" id="theme-settings-reset">
+        Reset to Defaults
+      </button>
+    </div>
+  </form>
+  {% from "partials/components.html" import feedback with context %} {{
+  feedback("theme-settings-feedback") }}
+</section>
+
+<section class="panel" id="theme-env-overrides">
+  <header class="panel-header">
+    <div>
+      <h2>Environment Overrides</h2>
+      <p class="chart-subtitle">
+        The following CSS variables are controlled via environment variables and
+        take precedence over database values.
+      </p>
+    </div>
+  </header>
+  {% if css_env_override_rows %}
+  <div class="table-container env-overrides-table">
+    <table aria-label="Environment-controlled theme variables">
+      <thead>
+        <tr>
+          <th scope="col">CSS Variable</th>
+          <th scope="col">Environment Variable</th>
+          <th scope="col">Value</th>
+        </tr>
+      </thead>
+      <tbody>
+        {% for row in css_env_override_rows %}
+        <tr>
+          <td><code>{{ row.css_key }}</code></td>
+          <td><code>{{ row.env_var }}</code></td>
+          <td><code>{{ row.value }}</code></td>
+        </tr>
+        {% endfor %}
+      </tbody>
+    </table>
+  </div>
+  {% else %}
+  <p class="empty-state">No environment overrides configured.</p>
+  {% endif %}
+</section>
+{% endblock %} {% block scripts %} {{ super() }}
+<script id="theme-settings-data" type="application/json">
+  {{ {
+    "variables": css_variables,
+    "defaults": css_defaults,
+    "envOverrides": css_env_overrides,
+    "envSources": css_env_override_rows
+  } | tojson }}
+</script>
+<script src="/static/js/settings.js"></script>
+{% endblock %}