ui : move mcp servers to the sidebar rail

The add menu keeps to what it attaches to the conversation, so the MCP
servers dialog moves to the sidebar rail and its menu entries and the
form callback they used go with it.

Assisted-by: pi:llama.cpp/DeepSeek-V4.1-Flash

tools/ui/src/lib/enums/ui.enums.ts

@@ -23,6 +23,7 @@ export enum ScrollCarouselVariant {
  * Sidebar icon strip actions handled directly by the sidebar.
  */
 export enum SidebarAction {
+	DISCOVER_MODELS = 'discover-models',
 	MANAGE_MODELS = 'manage-models',
 	MCP = 'mcp',
 	NEW_CHAT = 'new-chat',

tools/ui/src/lib/types/chat.d.ts

@@ -334,6 +334,5 @@ export interface ChatFormActionsContext {
 	readonly hasVideoModality: boolean;
 	readonly hasVisionModality: boolean;
 	onFileUpload?: () => void;
-	onMcpSettingsClick?: () => void;
 	onSystemPromptClick?: () => void;
 }