refactor(ext/shared): move View + PopupState to shared/popup-state.ts

Foundation for Plan C Phase 1: shared/state.ts (next task) needs to import
PopupState without creating a popup->shared circular dep. popup.ts now
re-exports from the new location so existing callers don't break in this
task. Task 1.4 will sweep them onto the canonical import path.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

extension/src/shared/popup-state.ts

@@ -0,0 +1,45 @@
+// State shared between popup and vault surfaces. Kept here (not in popup/) so
+// shared/state.ts can import without creating a popup→shared circular dep.
+
+import type {
+  Item,
+  ItemId,
+  ItemType,
+  ManifestEntry,
+  GeneratorRequest,
+  VaultSettings,
+} from './types';
+
+export type View =
+  | 'locked'
+  | 'list'
+  | 'detail'
+  | 'add'
+  | 'edit'
+  | 'settings'
+  | 'settings-vault'
+  | 'trash'
+  | 'devices'
+  | 'field-history';
+
+export interface PopupState {
+  view: View;
+  entries: Array<[ItemId, ManifestEntry]>;
+  selectedId: ItemId | null;
+  selectedItem: Item | null;
+  selectedIndex: number;
+  searchQuery: string;
+  activeGroup: string | null;
+  error: string | null;
+  loading: boolean;
+  // Captured tab snapshot taken at popup-open. Used by fill_credentials
+  // to guard against TOCTOU navigation — the SW re-checks this URL's
+  // hostname against the tab's live URL before forwarding fill_credentials
+  // to the content script. See router/popup-only.ts#handleFillCredentials.
+  capturedTabId: number | null;
+  capturedUrl: string;
+  newType: ItemType | null;
+  vaultSettings: VaultSettings | null;
+  generatorDefaults: GeneratorRequest | null;
+  historyItemId: ItemId | null;
+}