feat: implement template variables input functionality

- Create useTemplateValues hook to manage template variable state
- Support dynamic placeholder replacement in provider configs
- Add template parameter input UI in provider form
- Validate required template values before submission
- Auto-update config when template values change

src/components/providers/forms/hooks/index.ts

@@ -6,3 +6,4 @@ export { useCodexConfigState } from "./useCodexConfigState";
 export { useApiKeyLink } from "./useApiKeyLink";
 export { useCustomEndpoints } from "./useCustomEndpoints";
 export { useKimiModelSelector } from "./useKimiModelSelector";
+export { useTemplateValues } from "./useTemplateValues";