Manage the Slack digest in the admin

New settings area: the webhook lives in the database and is only shown
shortened afterwards, the environment variable stays as a fallback. A switch
decides whether internal entries travel, a button sends the digest right
away, and every run is recorded with period, count, projects, result and
who triggered it.

tests/setup.ts

@@ -13,6 +13,6 @@ rmSync(testStorage, { recursive: true, force: true })
 process.env.STORAGE_DIR = testStorage
 
 beforeEach(async () => {
-	await db.execute(sql`truncate table post_read, api_client, post_tag, tag, block, post, issue, media, project, brand, post_type restart identity cascade`)
+	await db.execute(sql`truncate table post_read, api_client, post_tag, tag, block, post, issue, media, project, brand, post_type, app_setting, report_run restart identity cascade`)
 	await insertDefaultPostTypes()
 })