web: spam check in call history

SD5 (14 §9.5): each incoming call keeps what the spam check knew when it
ended (saved answers and the FTC list only, no new lookup), so the badge
stays in call history after the saved answer expires. Hidden when the
viewer's contacts name the number. New admin guide page, spam-check.md.

Follow-up: the owner's checks with real keys and a real call (14 §9).

packages/shared/src/calls.ts

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: AGPL-3.0-or-later
 // Call history (02 calls, call_extensions; 04 §5.4, §7.3).
 import { z } from 'zod';
+import type { SpamCheck } from './spam.ts';
 
 export const CALL_DIRECTIONS = ['inbound', 'outbound', 'internal'] as const;
 export const CALL_STATUSES = [
@@ -43,6 +44,8 @@ export type CallDto = {
   answeredBy: { id: string; number: string; name: string } | null;
   talkSeconds: number;
   recordingId: string | null;
+  /** 14 §6: what the spam check knew as it ended; null when not checked or in the viewer's books. */
+  spam: SpamCheck | null;
 };
 
 /** One raw CDR leg, for the expanded row. */