Only send what is new, and lead with a picture

The window now starts at the last dispatch, so pressing send twice does not
repeat a digest. Cards prefer entries that have a cover, the newest one of
them opens the message as a full width image, and the page says when the
last digest went out.

tests/lib/report-settings.test.ts

@@ -121,3 +121,25 @@ describe('Bot-Token', () => {
 		expect(outcome.run).toMatchObject({ sent: false, detail: 'channel_not_found' })
 	})
 })
+
+describe('Doppelter Versand', () => {
+	it('schickt nach einem Versand nichts Zweites, solange nichts Neues erscheint', async () => {
+		const brand = await makeBrand()
+		const project = await makeProject(brand.id)
+
+		await makePost(project.id, { number: 1, slug: 'eins', status: 'published', publishAt: new Date() })
+		await writeSetting('slack.botToken', 'xoxb-1234')
+		await writeSetting('slack.channel', 'C123')
+
+		vi.stubGlobal('fetch', vi.fn(async () => new Response(
+			JSON.stringify({ ok: true, channel: 'C123', ts: '1785600000.000100' }),
+			{ headers: { 'content-type': 'application/json' } },
+		)))
+
+		const first = await runWeeklyReport({ origin, trigger: 'test' })
+		const second = await runWeeklyReport({ origin, trigger: 'test' })
+
+		expect(first.reason).toBe('sent')
+		expect(second.reason).toBe('nothing_published')
+	})
+})