Initial commit: thbd-portal, duplicated from elmi-portal

Rebranded for Thunderbird Portal (THBD): numbering prefix EL->TH, all
"ELMI"/"ЭЛМИ" UI strings genericized, ELMI's real contract templates and
company legal/bank details removed (not applicable to this company), fresh
VAPID keypair and encryption key, fresh single-migration schema history.
Same architecture as elmi-portal: Web Push notifications, unread-chat app
badge, cookie-session auth.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gh2UXUQUVBWroWEnn1FLFG

src/app/api/chat/conversations/route.ts

@@ -0,0 +1,35 @@
+export const runtime = "nodejs";
+
+import { NextResponse } from "next/server";
+import { z } from "zod";
+import { requireSession } from "@/lib/auth/require";
+import { listConversationsForUser, getOrCreateDirectConversation, createGroupConversation } from "@/lib/chat/service";
+
+export async function GET() {
+  const { session, response } = await requireSession();
+  if (!session) return response;
+  return NextResponse.json(await listConversationsForUser(session.user.id));
+}
+
+const schema = z.union([
+  z.object({ peerId: z.string().min(1) }),
+  z.object({ name: z.string().min(1), participantIds: z.array(z.string().min(1)).min(1) }),
+]);
+
+export async function POST(request: Request) {
+  const { session, response } = await requireSession();
+  if (!session) return response;
+
+  const parsed = schema.safeParse(await request.json().catch(() => null));
+  if (!parsed.success) {
+    return NextResponse.json({ error: "Некорректные данные" }, { status: 400 });
+  }
+
+  if ("peerId" in parsed.data) {
+    const conv = await getOrCreateDirectConversation(session.user.id, parsed.data.peerId);
+    return NextResponse.json(conv, { status: 201 });
+  }
+
+  const conv = await createGroupConversation(session.user.id, parsed.data.participantIds, parsed.data.name);
+  return NextResponse.json(conv, { status: 201 });
+}