Task #511: Fully remove Chat feature

Destructive removal per user confirmation ("حذف نهائي ما يرجع").

Removed:
- API: routes/conversations.ts, schema/conversations.ts, all chat
  socket handlers in src/index.ts, /admin/users/:id/dependents/
  conversations+messages endpoints, conversation/message dependency
  counts in users/stats routes.
- Web: pages/chat.tsx, /chat route, dock chat filter, MessageSquare
  icon and messages StatCard on home, all chat-related UI in
  notifications + admin (dependency badges, delete-dialog rows,
  UserDependentConversations/Messages sections, count map keys).
- Locales: nav.chat, home.stats.messages, full chat.* block,
  admin.deleteUser conv/msgCount, admin.users.counts.conv/msg,
  admin.audit.unit.conversation_*/message_*, admin.dependents.user*.
- OpenAPI spec: tags, all /conversations/* paths, conv/msg dependent
  paths, related schemas (ConversationWithDetails, MessageWithSender,
  UserDependentConversation/MessageItem+Page, etc.), UserProfile and
  UserDeletionConflict conv/msg fields, HomeStats.unreadMessages.
  Regenerated client via orval.
- Database: dropped message_reads, messages,
  conversation_participants, conversations (CASCADE); deleted
  notifications with related_type='conversation' or type='chat';
  deleted apps row with slug='chat'; ran drizzle push-force.
- Seed: removed chat:access permission + user-role assignment +
  seeded chat app entry from scripts/src/seed.ts.
- Tests: deleted conversations-leave.test.mjs; cleaned chat refs from
  list-dependency-counts, delete-force-warnings, audit-log-coverage,
  and admin-inline-dependency-counts (e2e) — replaced chat dependents
  with note dependents where needed for force-delete coverage.

Notes preserved: notes.tsx noConversationsYet/conversationWith refer
to NOTE THREADS (not chat) and were intentionally NOT touched.

executive-meetings.ts not modified per replit.md restriction.
Pre-existing flaky test failures in executive-meetings/group/etc
suites remain unrelated to this task.

scripts/src/seed.ts

@@ -43,7 +43,6 @@ async function main() {
     { name: "apps:manage", descriptionAr: "إدارة التطبيقات", descriptionEn: "Manage Apps" },
     { name: "services:manage", descriptionAr: "إدارة الخدمات", descriptionEn: "Manage Services" },
     { name: "users:manage", descriptionAr: "إدارة المستخدمين", descriptionEn: "Manage Users" },
-    { name: "chat:access", descriptionAr: "الوصول للمحادثات", descriptionEn: "Access Chat" },
     { name: "orders.receive", descriptionAr: "استلام الطلبات", descriptionEn: "Receive service orders" },
   ];
 
@@ -78,17 +77,6 @@ async function main() {
       .onConflictDoNothing();
   }
 
-  // Assign chat permission to user role
-  if (userRoleResolved && allInsertedPerms.length > 0) {
-    const chatPerm = allInsertedPerms.find((p) => p.name === "chat:access");
-    if (chatPerm) {
-      await db
-        .insert(rolePermissionsTable)
-        .values({ roleId: userRoleResolved.id, permissionId: chatPerm.id })
-        .onConflictDoNothing();
-    }
-  }
-
   // Assign orders:receive permission to order_receiver role
   if (orderReceiverResolved && allInsertedPerms.length > 0) {
     const ordersPerm = allInsertedPerms.find((p) => p.name === "orders.receive");
@@ -170,19 +158,6 @@ async function main() {
       isSystem: true,
       sortOrder: 1,
     },
-    {
-      slug: "chat",
-      nameAr: "المحادثات",
-      nameEn: "Chat",
-      descriptionAr: "تواصل مع زملائك",
-      descriptionEn: "Connect with your colleagues",
-      iconName: "MessageCircle",
-      route: "/chat",
-      color: "#22c55e",
-      isActive: true,
-      isSystem: true,
-      sortOrder: 2,
-    },
     {
       slug: "notifications",
       nameAr: "الإشعارات",