refactor(web): restructure to feature-based architecture with zustand stores

- Remove tab system entirely (tab-store, tab-bar, tab-link)
- Split monolithic AuthContext into zustand auth + workspace stores
- Move issue components/config to features/issues/
- Move WebSocket provider to features/realtime/
- Move api.ts to shared/
- Migrate all consumers from useAuth() to direct store imports
- Simplify sidebar: replace hand-built dropdown with shadcn DropdownMenu,
  replace custom layout wrapper with SidebarInset
- Remove unused @multica/store and @multica/hooks dependencies
- Add @/ path alias and zustand dependency
- Update CLAUDE.md with feature-based architecture conventions

Net change: +293 / -2435 lines

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

apps/web/features/workspace/hooks.ts

@@ -0,0 +1,36 @@
+"use client";
+
+import { useWorkspaceStore } from "./store";
+
+export function useActorName() {
+  const members = useWorkspaceStore((s) => s.members);
+  const agents = useWorkspaceStore((s) => s.agents);
+
+  const getMemberName = (userId: string) => {
+    const m = members.find((m) => m.user_id === userId);
+    return m?.name ?? "Unknown";
+  };
+
+  const getAgentName = (agentId: string) => {
+    const a = agents.find((a) => a.id === agentId);
+    return a?.name ?? "Unknown Agent";
+  };
+
+  const getActorName = (type: string, id: string) => {
+    if (type === "member") return getMemberName(id);
+    if (type === "agent") return getAgentName(id);
+    return "System";
+  };
+
+  const getActorInitials = (type: string, id: string) => {
+    const name = getActorName(type, id);
+    return name
+      .split(" ")
+      .map((w) => w[0])
+      .join("")
+      .toUpperCase()
+      .slice(0, 2);
+  };
+
+  return { getMemberName, getAgentName, getActorName, getActorInitials };
+}