feat: add price filter and dynamic slider to catalog

- Implemented JavaScript-based price slider for catalog filtering
- Updated catalog views to handle min/max price inputs and compute slider bounds
- Enhanced templates (`index.html`, `side-bar.html`) with filtering form and updated URLs
- Added CSS for price slider styling and form layout
- Introduced utility functions for URL building and price parsing
- Expanded tests for price filtering, sliders, and sidebar active states
- Updated context processor and header for dynamic navigation with price filters

templates/catalog/_fragments/side-bar.html

@@ -1,9 +1,9 @@
 <aside>
     <section class="categories a-section">
         <h2>Категории</h2>
-        <a href="/catalog/" class="category {% if selected_category.id == None %}active{% endif %}">Все товары</a>
+        <a href="{{ all_items_url }}" class="category {% if selected_category.id == None %}active{% endif %}">Все товары</a>
         {% for category in categories %}
-            <a href="/catalog/{{ category.slug }}/" class="category {% if selected_category.id == category.slug %}active{% endif %}">
+            <a href="{{ category.catalog_url }}" class="category {% if selected_category.id == category.slug %}active{% endif %}">
                 {{ category.name }}
             </a>
         {% empty %}
@@ -14,11 +14,11 @@
     <section class="sub-categories a-section">
         <h2>Подкатегории</h2>
         {% if selected_category.id != None %}
-            <a href="/catalog/{{ selected_category.id }}/" class="category {% if selected_subcategory.id == None %}active{% endif %}">
+            <a href="{{ selected_category_url }}" class="category {% if selected_subcategory.id == None %}active{% endif %}">
                 Все подкатегории
             </a>
             {% for subcategory in subcategories %}
-                <a href="/catalog/{{ selected_category.id }}/?subcategory={{ subcategory.slug }}" class="category {% if selected_subcategory.id == subcategory.slug %}active{% endif %}">
+                <a href="{{ subcategory.catalog_url }}" class="category {% if selected_subcategory.id == subcategory.slug %}active{% endif %}">
                     {{ subcategory.name }}
                 </a>
             {% empty %}
@@ -29,9 +29,54 @@
         {% endif %}
     </section>
 
-    <form action="">
+    <form action="{{ price_filter_action }}" method="get" class="catalog-filter-form">
+        <input type="hidden" name="q" value="{{ current_search_query }}">
+        {% if selected_subcategory.id != None %}
+            <input type="hidden" name="subcategory" value="{{ selected_subcategory.id }}">
+        {% endif %}
         <section class="a-section cost-section">
             <h2>Стоимость</h2>
+            <div
+                class="catalog-price-slider"
+                data-price-slider
+                data-min-bound="{{ price_slider_min_bound }}"
+                data-max-bound="{{ price_slider_max_bound }}"
+            >
+                <input type="hidden" name="min_price" value="{{ current_min_price }}" data-price-hidden-min>
+                <input type="hidden" name="max_price" value="{{ current_max_price }}" data-price-hidden-max>
+
+                <div class="catalog-price-slider__values" aria-live="polite">
+                    <span data-price-label-min>{{ price_slider_selected_min }} руб.</span>
+                    <span data-price-label-max>{{ price_slider_selected_max }} руб.</span>
+                </div>
+
+                <div class="catalog-price-slider__controls">
+                    <div class="catalog-price-slider__track">
+                        <div class="catalog-price-slider__track-fill" data-price-track-fill></div>
+                    </div>
+                    <input
+                        type="range"
+                        min="{{ price_slider_min_bound }}"
+                        max="{{ price_slider_max_bound }}"
+                        step="0.01"
+                        value="{{ price_slider_selected_min }}"
+                        class="catalog-price-slider__range"
+                        aria-label="Минимальная цена"
+                        data-price-range-min
+                    >
+                    <input
+                        type="range"
+                        min="{{ price_slider_min_bound }}"
+                        max="{{ price_slider_max_bound }}"
+                        step="0.01"
+                        value="{{ price_slider_selected_max }}"
+                        class="catalog-price-slider__range"
+                        aria-label="Максимальная цена"
+                        data-price-range-max
+                    >
+                </div>
+            </div>
+            <button type="submit" class="catalog-filter-submit">Применить</button>
         </section>
 
         <section class="a-section color-section">