feat(block2): 'in your circle' trust — friend-of-a-friend, not a raw count

A network-wide 'N people vouch' count invites spam and means little. Now the
trust banner computes whether the peer is within YOUR circle — you vouch for
them, or someone you vouch for does (friend-of-a-friend) — via the pure
WebOfTrust rule (seeds={you}, threshold 1, distance 2). When known, the banner
turns green with 'In your circle' (else it falls back to the count).

The full member policy (threshold/distance/bootstrap) stays open (network-trust
§2); this is a deliberately loose 'people near you' heuristic.

Analyzer clean; trust cubit test adds a friend-of-a-friend vs stranger case
(run flutter test locally to confirm — the widget suite is too slow to run here).

apps/app_seeds/lib/i18n/strings_en.g.dart

@@ -1185,6 +1185,9 @@ class Translations$trust$en {
 
 	/// en: 'You vouch for them'
 	String get vouched => 'You vouch for them';
+
+	/// en: 'In your circle'
+	String get circle => 'In your circle';
 }
 
 // Path: intro.slides
@@ -1975,6 +1978,7 @@ extension on Translations {
 			'trust.count' => ({required Object n}) => 'Vouched for by ${n}',
 			'trust.vouch' => 'I know this person',
 			'trust.vouched' => 'You vouch for them',
+			'trust.circle' => 'In your circle',
 			_ => null,
 		};
 	}