Implement dashboard composition (task 20)

- Add default_dashboard_layout jsonb to users + migration 0007
- Create _core/manifest.tsx with core.activity placeholder widget
- Register core manifest alongside calendar/lists/notes
- Update all three module manifests with real async server-component
  widget renders (upcoming events, month view, list items, notes)
- Add src/lib/dashboard.ts: computeDefaultLayout greedy packer +
  parseDashboardLayout Zod validator
- Build src/app/page.tsx: 12-col CSS Grid, static smColSpan lookup,
  per-widget Suspense for parallel loading, generic widget.render()
  dispatch — no widgetId branches
- Add tests/e2e/dashboard.spec.ts; all 4 E2E specs pass

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/modules/lists/manifest.tsx

@@ -1,10 +1,49 @@
-import type { ModuleManifest } from "../_core/module";
+import type { ModuleManifest, WidgetContext } from "../_core/module";
 import { z } from "zod";
 import { addItemToDefaultList } from "./server/actions";
-import { listLists, searchItems, searchLists } from "./server/queries";
+import { listLists, listWidgetItems, searchItems, searchLists } from "./server/queries";
 
 const listIdsSchema = z.union([z.literal("all"), z.array(z.string().uuid())]);
 
+const listWidgetConfigSchema = z.object({
+  listIds: listIdsSchema,
+  showCompleted: z.boolean(),
+  limit: z.number().int().min(1).max(50).optional(),
+});
+
+async function ListWidget({ config }: { config: unknown; ctx: WidgetContext }) {
+  const parsed = listWidgetConfigSchema.parse(config);
+  const items = await listWidgetItems({
+    listIds: parsed.listIds,
+    showCompleted: parsed.showCompleted,
+    limit: parsed.limit ?? 10,
+  });
+
+  if (items.length === 0) {
+    return (
+      <p className="text-sm text-muted-foreground">
+        {parsed.showCompleted ? "No items" : "No open items"}
+      </p>
+    );
+  }
+
+  return (
+    <ul className="space-y-1">
+      {items.map((item) => (
+        <li key={item.id} className="flex items-center gap-2 text-sm">
+          <span
+            className={`h-4 w-4 shrink-0 rounded-sm border border-border ${item.done ? "bg-muted" : ""}`}
+          />
+          <span className={`truncate ${item.done ? "text-muted-foreground line-through" : ""}`}>
+            {item.text}
+          </span>
+          <span className="ml-auto shrink-0 text-xs text-muted-foreground">{item.listName}</span>
+        </li>
+      ))}
+    </ul>
+  );
+}
+
 const manifest: ModuleManifest = {
   id: "lists",
   name: "Lists",
@@ -34,11 +73,7 @@ const manifest: ModuleManifest = {
       defaultSize: { w: 4, h: 3 },
       minSize: { w: 3, h: 2 },
       defaultPriority: 30,
-      configSchema: z.object({
-        listIds: listIdsSchema,
-        showCompleted: z.boolean(),
-        limit: z.number().int().min(1).max(50).optional(),
-      }),
+      configSchema: listWidgetConfigSchema,
       defaultConfig: { listIds: "all", showCompleted: false },
       resolveConfigOptions: async () => ({
         lists: (await listLists()).map((list) => ({
@@ -47,20 +82,7 @@ const manifest: ModuleManifest = {
           name: list.name,
         })),
       }),
-      render: ({ config }) => {
-        const parsed = z
-          .object({
-            listIds: listIdsSchema,
-            showCompleted: z.boolean(),
-            limit: z.number().int().min(1).max(50).optional(),
-          })
-          .parse(config);
-        return (
-          <div className="text-sm text-muted-foreground">
-            {parsed.showCompleted ? "List items" : "Open list items"}
-          </div>
-        );
-      },
+      render: (props) => <ListWidget {...props} />,
     },
   ],
   quickAdds: [