✨ feat: Enhance Channel Model Management UI

Summary
• Introduced standalone `ModelSelectModal.jsx` for selecting channel models
• Fetch-list now opens modal instead of in-place select, keeping EditChannelModal lean

Modal Features
1. Search bar with `IconSearch`, keyboard clear & mobile full-screen support
2. Tab layout (“New Models” / “Existing Models”) displayed next to title, responsive wrapping
3. Models grouped by vendor via `getModelCategories` and rendered inside always-expanded `Collapse` panels
4. Per-category checkbox in panel extra area for bulk select / deselect
5. Footer checkbox for bulk select of all models in current tab, with real-time counter
6. Empty state uses `IllustrationNoResult` / `IllustrationNoResultDark` for visual consistency
7. Accessible header/footer paddings aligned with Semi UI defaults

Fixes & Improvements
• All indeterminate and full-select states handled correctly
• Consistent “selected X / Y” stats synced with active tab, not global list
• All panels now controlled via `activeKey`, ensuring they remain expanded
• Search, vendor grouping, and responsive layout tested across mobile & desktop

These changes modernise the channel model management workflow and prepare the codebase for upcoming upstream-ratio integration.

web/src/i18n/locales/en.json

@@ -1799,5 +1799,10 @@
   "显示第": "Showing",
   "条 - 第": "to",
   "条，共": "of",
-  "条": "items"
+  "条": "items",
+  "选择模型": "Select model",
+  "已选择 {{selected}} / {{total}}": "Selected {{selected}} / {{total}}",
+  "新获取的模型": "New models",
+  "已有的模型": "Existing models",
+  "搜索模型": "Search models"
 }