feat(lists): drag tasks and list entries onto another list; remember open list and view; live pill in lists

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/lib/viewSession.ts

@@ -0,0 +1,20 @@
+// View state for this browser tab that survives switching between the app's tabs (the views
+// remount), like the workspace's open note: which list was open, list or Kanban view
+const PREFIX = 'mindsift_view:';
+
+export function readViewSession<T extends object>(view: string): Partial<T> {
+  try {
+    const raw = JSON.parse(sessionStorage.getItem(PREFIX + view) || '{}');
+    return raw && typeof raw === 'object' ? raw : {};
+  } catch {
+    return {};
+  }
+}
+
+export function writeViewSession<T extends object>(view: string, state: T) {
+  try {
+    sessionStorage.setItem(PREFIX + view, JSON.stringify(state));
+  } catch {
+    // storage blocked: the view simply starts fresh
+  }
+}