fix(web): keep the settings dialog one size and move billing into it (BUG-554)

The four account panes now share a fixed frame, chart profiles open as list then detail, and membership lives in the homepage dialog instead of a separate page.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/hooks/use-rectification-surface.ts

@@ -15,6 +15,7 @@ import {
   type ChatSession,
   type Message,
   type OnboardingStep,
+  type OpenAccountDialogOptions,
   type Profile,
   type Theme,
 } from "@/lib/home-types";
@@ -72,7 +73,7 @@ export type RectificationSurfaceParams = {
   setSessions: Dispatch<SetStateAction<ChatSession[]>>;
   uiPreview: MutableRefObject<boolean>;
   updateSession: (sessionId: string, change: (session: ChatSession) => ChatSession) => void;
-  openAccountDialog: (dialog: AccountDialog, returnTarget?: HTMLButtonElement | null) => void;
+  openAccountDialog: (dialog: AccountDialog, options?: HTMLButtonElement | null | OpenAccountDialogOptions) => void;
   refreshAccount: () => Promise<void>;
   rectificationSessionOpenerRef: MutableRefObject<(exactSessionId: string) => Promise<void>>;
 };