feat: pagina Conversazioni — inbox unificata messaggi clienti

Nuova pagina admin /admin/conversazioni: vista WhatsApp-style (lista
conversazioni a sinistra, thread + risposta a destra) che aggrega i
messaggi di tutti i clienti dalla tabella comments, cross-cliente.

- Migration additiva 0014: clients.admin_last_read_at per tracciare
  letto/non-letto (pallini + badge in sidebar). Applicata a prod.
- conversations-queries.ts: aggregazione entity_id → cliente
  (general/phase/task/deliverable), getConversations /
  getConversationThread / getUnreadConversationsCount.
- Risposte admin salvate come commento "general" (visibili anche nella
  chat cliente e nel CommentsTab della scheda).
- Voce di menu + badge non-letti (AdminSidebar/AdminShell/layout).
- Token semantici per dual light/dark; refresh manuale (no polling).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/admin/AdminSidebar.tsx

@@ -13,12 +13,14 @@ import {
   LogOut,
   Zap,
   FileText,
+  MessageSquare,
 } from "lucide-react";
 import ThemeToggle from "@/components/ThemeToggle";
 import { cn } from "@/lib/utils";
 
 const NAV_ITEMS = [
   { href: "/admin",               label: "Dashboard",    icon: LayoutDashboard, exact: true },
+  { href: "/admin/conversazioni", label: "Conversazioni", icon: MessageSquare },
   { href: "/admin/pipeline",      label: "Pipeline",     icon: Zap },
   { href: "/admin/clients",       label: "Clienti",      icon: Users },
   { href: "/admin/projects",      label: "Progetti",     icon: FolderOpen },
@@ -28,7 +30,13 @@ const NAV_ITEMS = [
   { href: "/admin/impostazioni",  label: "Impostazioni", icon: Settings },
 ];
 
-export function AdminSidebar({ collapsed = false }: { collapsed?: boolean }) {
+export function AdminSidebar({
+  collapsed = false,
+  unreadConversations = 0,
+}: {
+  collapsed?: boolean;
+  unreadConversations?: number;
+}) {
   const pathname = usePathname();
 
   const isActive = (href: string, exact?: boolean) =>
@@ -64,6 +72,10 @@ export function AdminSidebar({ collapsed = false }: { collapsed?: boolean }) {
       <nav className="flex-1 px-2 py-4 flex flex-col gap-0.5">
         {NAV_ITEMS.map(({ href, label, icon: Icon, exact }) => {
           const active = isActive(href, exact);
+          const badge =
+            href === "/admin/conversazioni" && unreadConversations > 0
+              ? unreadConversations
+              : 0;
           return (
             <Link
               key={href}
@@ -77,12 +89,22 @@ export function AdminSidebar({ collapsed = false }: { collapsed?: boolean }) {
                   : "text-white/65 hover:text-white hover:bg-white/10"
               )}
             >
-              <Icon
-                size={16}
-                strokeWidth={1.8}
-                className="shrink-0"
-              />
-              {!collapsed && <span className="whitespace-nowrap">{label}</span>}
+              <span className="relative shrink-0">
+                <Icon size={16} strokeWidth={1.8} className="shrink-0" />
+                {badge > 0 && collapsed && (
+                  <span className="absolute -top-1.5 -right-1.5 w-2 h-2 rounded-full bg-emerald-500 ring-2 ring-[#1A463C]" />
+                )}
+              </span>
+              {!collapsed && (
+                <span className="flex-1 flex items-center justify-between gap-2 min-w-0">
+                  <span className="whitespace-nowrap">{label}</span>
+                  {badge > 0 && (
+                    <span className="shrink-0 min-w-[18px] h-[18px] px-1.5 inline-flex items-center justify-center rounded-full bg-emerald-500 text-white text-[10px] font-bold">
+                      {badge}
+                    </span>
+                  )}
+                </span>
+              )}
             </Link>
           );
         })}