feat(app): sidebar favorites, drag-reorder, and delete-with-confirm

- FAVORITES section at the top collects pinned workspaces (removed from their
  group listing); a star toggle on each row pins/unpins via setWorkspaceMeta.
- Drag-to-reorder within a section using raw pointer events (HTML5 DnD is
  unreliable in the macOS WKWebView), with a drop-line indicator; on drop the
  section's `order` is reassigned sequentially and persisted. Cross-section
  drops are ignored (group membership unchanged).
- Trash icon on row hover opens a ConfirmDelete modal that shows the live
  terminal count and warns before terminating them, then calls close_workspace
  and re-points the active workspace.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/src/socketBridge.ts

@@ -149,13 +149,14 @@ export async function closeWorkspaceCmd(workspaceId: string): Promise<void> {
   await invoke("close_workspace", { workspaceId });
 }
 
-export async function setWorkspaceMeta(workspaceId: string, meta: { name?: string; groupId?: string | null; unread?: boolean; order?: number }): Promise<void> {
+export async function setWorkspaceMeta(workspaceId: string, meta: { name?: string; groupId?: string | null; unread?: boolean; order?: number; pinned?: boolean }): Promise<void> {
   await invoke("set_workspace_meta", {
     workspaceId,
     name: meta.name ?? null,
     groupId: meta.groupId === undefined ? null : meta.groupId,
     unread: meta.unread ?? null,
     order: meta.order ?? null,
+    pinned: meta.pinned ?? null,
   });
 }