Add CSPT entity, processed CSS source type, reverse filter, and UI improvements

- Add Color Strip Processing Template (CSPT) entity: reusable filter chains
  for 1D LED strip postprocessing (backend, storage, API, frontend CRUD)
- Add "processed" color strip source type that wraps another CSS source and
  applies a CSPT filter chain (dataclass, stream, schema, modal, cards)
- Add Reverse filter for strip LED order reversal
- Add CSPT and processed CSS nodes/edges to visual graph editor
- Add CSPT test preview WS endpoint with input source selection
- Add device settings CSPT template selector (add + edit modals with hints)
- Use icon grids for palette quantization preset selector in filter lists
- Use EntitySelect for template references and test modal source selectors
- Fix filters.css_filter_template.desc missing localization
- Fix icon grid cell height inequality (grid-auto-rows: 1fr)
- Rename "Processed" subtab to "Processing Templates"
- Localize all new strings (en/ru/zh)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/wled_controller/templates/modals/cspt-modal.html

@@ -0,0 +1,40 @@
+<!-- Color Strip Processing Template Modal -->
+<div id="cspt-modal" class="modal" role="dialog" aria-modal="true" aria-labelledby="cspt-modal-title">
+    <div class="modal-content">
+        <div class="modal-header">
+            <h2 id="cspt-modal-title" data-i18n="css_processing.add">Add Strip Processing Template</h2>
+            <button class="modal-close-btn" onclick="closeCSPTModal()" title="Close" data-i18n-aria-label="aria.close">&#x2715;</button>
+        </div>
+        <div class="modal-body">
+            <input type="hidden" id="cspt-id">
+            <form id="cspt-form">
+                <div class="form-group">
+                    <label for="cspt-name" data-i18n="css_processing.name">Template Name:</label>
+                    <input type="text" id="cspt-name" data-i18n-placeholder="css_processing.name_placeholder" placeholder="My Strip Processing Template" required>
+                    <div id="cspt-tags-container"></div>
+                </div>
+
+                <!-- Dynamic filter list -->
+                <div id="cspt-filter-list" class="pp-filter-list"></div>
+
+                <!-- Add filter control -->
+                <div class="pp-add-filter-row">
+                    <select id="cspt-add-filter-select" class="pp-add-filter-select">
+                        <option value="" data-i18n="filters.select_type">Select filter type...</option>
+                    </select>
+                </div>
+
+                <div class="form-group">
+                    <label for="cspt-description" data-i18n="css_processing.description_label">Description (optional):</label>
+                    <input type="text" id="cspt-description" data-i18n-placeholder="css_processing.description_placeholder" placeholder="Describe this template...">
+                </div>
+
+                <div id="cspt-error" class="error-message" style="display: none;"></div>
+            </form>
+        </div>
+        <div class="modal-footer">
+            <button class="btn btn-icon btn-secondary" onclick="closeCSPTModal()" title="Cancel" data-i18n-aria-label="aria.cancel">&#x2715;</button>
+            <button class="btn btn-icon btn-primary" onclick="saveCSPT()" title="Save" data-i18n-aria-label="aria.save">&#x2713;</button>
+        </div>
+    </div>
+</div>