Implement knowledge base page routing and enhance ComponentsKnowledgePage

- Update the main knowledge page to support a list mode.
- Add new pages for creating and editing knowledge bases, utilizing the ComponentsKnowledgePage component with appropriate modes.
- Introduce a new API method for retrieving knowledge base details by ID.
- Enhance the ComponentsKnowledgePage to handle different modes (list, create, edit) and improve user interaction with knowledge bases.

frontend/src/components/pages/AssistantPage.tsx

@@ -3041,7 +3041,9 @@ function TextAreaField({
         placeholder={placeholder}
         onChange={(event) => onChange(event.target.value)}
         rows={rows}
-        className="resize-none border-hairline-strong bg-background text-foreground placeholder:text-muted-soft"
+        // Override ui/textarea's field-sizing-content so `rows` sets a real height
+        // instead of collapsing to min-h-16 when the value is short.
+        className="field-sizing-fixed min-h-32 resize-y border-hairline-strong bg-background text-foreground placeholder:text-muted-soft"
       />
     </label>
   );