fix(dashboard): retarget feed footer to /chronik + render rollup rows

- "Alle anzeigen" link now goes to /chronik (was /documents — the dead-end
  bug called out in #285).
- Rollup rows (count > 1) render a primary-colored count badge plus a
  compound timestamp line: "14. Apr. · 14:02–14:32" (en-dash U+2013).
- Singleton rows render the existing "14. Apr. 2026" date line.
- BLOCK_REVIEWED now has a verb mapping (re-using the annotation verb until
  the spec pins a distinct copy).
- Three new spec cases: rollup count badge + en-dash range, no badge on
  singletons, /chronik link assertion.

Part of #285.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/DashboardActivityFeed.svelte.spec.ts

@@ -17,7 +17,8 @@ const baseItem: ActivityFeedItemDTO = {
 	documentId: 'doc-1',
 	documentTitle: 'Brief 1920',
 	happenedAt: '2026-04-19T10:00:00Z',
-	youMentioned: false
+	youMentioned: false,
+	count: 1
 };
 
 describe('DashboardActivityFeed', () => {
@@ -39,4 +40,30 @@ describe('DashboardActivityFeed', () => {
 		const section = page.getByText('Kommentare & Aktivität');
 		await expect.element(section).toBeInTheDocument();
 	});
+
+	it('renders count badge and en-dash time range for rollup rows (count > 1)', async () => {
+		const rollup: ActivityFeedItemDTO = {
+			...baseItem,
+			count: 20,
+			happenedAtUntil: '2026-04-19T10:32:00Z'
+		};
+		render(DashboardActivityFeed, { feed: [rollup] });
+		const badge = page.getByTestId('feed-rollup-count');
+		await expect.element(badge).toHaveTextContent('20');
+		// "–" is U+2013 en-dash
+		const stamp = page.getByText(/\u2013/);
+		await expect.element(stamp).toBeInTheDocument();
+	});
+
+	it('does not render count badge for singleton rows (count === 1)', async () => {
+		render(DashboardActivityFeed, { feed: [baseItem] });
+		const badge = page.getByTestId('feed-rollup-count');
+		await expect.element(badge).not.toBeInTheDocument();
+	});
+
+	it('links the "show all" footer to /chronik, not /documents', async () => {
+		render(DashboardActivityFeed, { feed: [] });
+		const link = page.getByRole('link', { name: /alle anzeigen/i });
+		await expect.element(link).toHaveAttribute('href', '/chronik');
+	});
 });