finish T-235 (persisted activity fold level); close T-132 via Q-34

T-235: app-scoped kActivityFoldLevelKey + a claude.activity.fold-level command
that cycles none→tools→thinking→everything; ClaudePane + team_panel_host read it
and re-fold live via the settings notifier. Unit tests for the helpers.

T-132 cleanup: the one blocked item (account/team token budget) is detached
(T-158), reframed as Q-34 'how + when to surface the budget given upstream
doesn't expose it', with T-158 as its backlog resolver. T-132 closed — all
doable work delivered.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/builtin/claude/src/activity_cluster.dart

@@ -30,6 +30,18 @@ enum FoldLevel {
   everything,
 }
 
+/// Settings key for the persisted activity-card fold level (T-235). App-scoped:
+/// a personal viewing preference, not per-repo.
+const String kActivityFoldLevelKey = 'app.claude.activityFoldLevel';
+
+/// Parse a stored fold-level name back to a [FoldLevel], defaulting to L1
+/// ([FoldLevel.tools]) for null/unknown values.
+FoldLevel foldLevelFromName(String? name) => FoldLevel.values.firstWhere((l) => l.name == name, orElse: () => FoldLevel.tools);
+
+/// The next fold level in the cycle none → tools → thinking → everything → none
+/// (T-235), for the toggle command.
+FoldLevel nextFoldLevel(FoldLevel level) => FoldLevel.values[(level.index + 1) % FoldLevel.values.length];
+
 /// A unit the conversation view renders: either a single first-class item or
 /// a folded run of meta items.
 sealed class RenderGroup {