fix: mention closure, onSettled invalidation, cleanup singleton

- Fix Tiptap mention: pass QueryClient via closure from ContentEditor
  instead of getQueryClient() singleton (resolves @mention empty list)
- Add onSettled invalidation to useUpdateIssue (prevents cache drift
  with staleTime: Infinity + self-event WS filter)
- Add cache shape comment to issueListOptions (select transforms
  ListIssuesResponse → Issue[], but cache stores raw response)
- Memoize sidebar inbox dedup computation
- Remove dead getQueryClient/setQueryClient singleton + window property
- Remove ActorSync component and _members/_agents Zustand mirror
  (superseded by closure approach)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/core/issues/mutations.ts

@@ -60,6 +60,9 @@ export function useUpdateIssue() {
       if (ctx?.prevDetail)
         qc.setQueryData(issueKeys.detail(wsId, ctx.id), ctx.prevDetail);
     },
+    onSettled: (_data, _err, vars) => {
+      qc.invalidateQueries({ queryKey: issueKeys.detail(wsId, vars.id) });
+    },
   });
 }
 

apps/web/core/issues/queries.ts

@@ -12,6 +12,11 @@ export const issueKeys = {
     ["issues", "subscribers", issueId] as const,
 };
 
+/**
+ * CACHE SHAPE NOTE: The raw cache stores ListIssuesResponse ({ issues, total }),
+ * but `select` transforms it to Issue[] for consumers. Mutations and ws-updaters
+ * must use setQueryData<ListIssuesResponse>(...) — NOT setQueryData<Issue[]>.
+ */
 export function issueListOptions(wsId: string) {
   return queryOptions({
     queryKey: issueKeys.list(wsId),