Report what Slack actually answers

The lookup swallowed Slack's error and the interface guessed at a cause.
It now shows the raw reason, widens the search window to six hours and
falls back to matching the message prefix.

src/lib/admin-settings.ts

@@ -132,21 +132,27 @@ export async function performDeleteMessage(viewer: Viewer, formData: FormData):
 		return invalid('runNoChannel')
 	}
 
-	const messageTs = run.messageTs ?? await findMessageTs({
-		token,
-		channel,
-		text: reportText({ from: run.fromAt, to: run.toAt, total: run.total }),
-		around: run.createdAt,
-	})
+	let messageTs = run.messageTs
 
 	if (!messageTs) {
-		return invalid('runNotFound')
+		const lookup = await findMessageTs({
+			token,
+			channel,
+			text: reportText({ from: run.fromAt, to: run.toAt, total: run.total }),
+			around: run.createdAt,
+		})
+
+		if (!lookup.ok) {
+			return invalid('slackSaid', { detail: lookup.detail })
+		}
+
+		messageTs = lookup.messageTs
 	}
 
 	const result = await deleteFromSlack(token, channel, messageTs)
 
 	if (!result.ok) {
-		return invalid('runDeleteFailed')
+		return invalid('slackSaid', { detail: result.detail })
 	}
 
 	await markReportRunDeleted(run.id)