feat(ext/popup): add pop-out to tab for forms

Forms can now be opened in a full browser tab via the ⤴ button,
solving Chrome's popup closure on file picker interaction. Deep
linking via URL params preserves view, item type, and item ID.

Also removes the unused dropdown picker code from item-list.ts.

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

extension/src/popup/popup.ts

@@ -28,6 +28,29 @@ export function escapeHtml(str: string): string {
     .replace(/'/g, ''');
 }
 
+// --- Pop out to tab ---
+
+export function popOutToTab(): void {
+  const state = getState();
+  const params = new URLSearchParams();
+  params.set('view', state.view);
+  if (state.newType) params.set('type', state.newType);
+  if (state.selectedId) params.set('id', state.selectedId);
+  chrome.tabs.create({ url: `popup.html?${params.toString()}` });
+  window.close();
+}
+
+function parseUrlParams(): { view?: View; type?: string; id?: string } | null {
+  const params = new URLSearchParams(window.location.search);
+  const view = params.get('view');
+  if (!view) return null;
+  return {
+    view: view as View,
+    type: params.get('type') ?? undefined,
+    id: params.get('id') ?? undefined,
+  };
+}
+
 // --- State ---
 
 export type View = 'locked' | 'list' | 'detail' | 'add' | 'edit' | 'settings' | 'settings-vault' | 'trash' | 'devices' | 'field-history';
@@ -214,6 +237,28 @@ async function init(): Promise<void> {
           currentState.vaultSettings = vs;
           currentState.generatorDefaults = vs.generator_defaults;
         }
+
+        // Check URL params for deep linking (when opened in tab)
+        const urlParams = parseUrlParams();
+        if (urlParams) {
+          currentState.entries = listData.items;
+          if (urlParams.view === 'add' && urlParams.type) {
+            currentState.newType = urlParams.type as import('../shared/types').ItemType;
+            navigate('add');
+            return;
+          }
+          if ((urlParams.view === 'edit' || urlParams.view === 'detail') && urlParams.id) {
+            // Fetch the item
+            const itemResp = await sendMessage({ type: 'get_item', id: urlParams.id });
+            if (itemResp.ok) {
+              currentState.selectedId = urlParams.id;
+              currentState.selectedItem = (itemResp.data as { item: Item }).item;
+              navigate(urlParams.view);
+              return;
+            }
+          }
+        }
+
         navigate('list', { entries: listData.items });
         return;
       }