✨ refactor: unify model-select searching & UX across the dashboard

This patch standardises how all “model” (and related) `<Select>` components handle searching.

Highlights
• Added a shared helper `modelSelectFilter` to `helpers/utils.js` – performs case-insensitive  value-based matching, independent of ReactNode labels.
• Removed the temporary `helpers/selectFilter.js`; all components now import from the core helpers barrel.
• Updated Selects to use the new filter *and* set `autoClearSearchValue={false}` so the query text is preserved after a choice is made.

Affected components
• Channel editor (EditChannelModal) – channel type & model lists
• Tag editor (EditTagModal) – model list
• Token editor (EditTokenModal) – model-limit list
• Playground SettingsPanel – model selector

Benefits
✓ Consistent search behaviour across the app
✓ Better user experience when selecting multiple items
✓ Cleaner codebase with one canonical filter implementation

web/src/components/table/tokens/modals/EditTokenModal.jsx

@@ -26,6 +26,7 @@ import {
   renderGroupOption,
   renderQuotaWithPrompt,
   getModelCategories,
+  modelSelectFilter,
 } from '../../../../helpers';
 import { useIsMobile } from '../../../../hooks/common/useIsMobile.js';
 import {
@@ -513,7 +514,8 @@ const EditTokenModal = (props) => {
                       multiple
                       optionList={models}
                       extraText={t('非必要，不建议启用模型限制')}
-                      filter
+                      filter={modelSelectFilter}
+                      autoClearSearchValue={false}
                       searchPosition='dropdown'
                       showClear
                       style={{ width: '100%' }}