feat(vpn): VPN on-demand Tailscale + agent studioE5 standalone

- Agent studioE5 standalone en Go (console + systray)
- VPN on-demand via tailscaled + tailscale up (authkey Headscale)
- Resolver/serveur dans le tailnet studioe5
- Caddy on-demand TLS pour les instances
- Nouveaux endpoints serveur /api/internal/send-to-node
- Suppression des anciens binaires edubox-agent
- Suivi dans SUIVI_VPN_ONDEMAND.md

server/app/api/check-domain/route.ts

@@ -11,7 +11,10 @@ export async function GET(req: NextRequest) {
     return NextResponse.json({ ok: false }, { status: 400 });
   }
 
-  if (domain === MAIN_DOMAIN || domain === `headscale.${MAIN_DOMAIN}`) {
+  if (
+    domain === MAIN_DOMAIN ||
+    domain === `headscale.${MAIN_DOMAIN}`
+  ) {
     return NextResponse.json({ ok: true });
   }
 

server/app/api/download/route.ts

@@ -1,12 +1,13 @@
 import { NextResponse } from "next/server";
 
 const AGENT_VERSION = "0.3.0";
+const AGENT_BIN_NAME = "studioE5-agent";
 
 export async function GET() {
   return NextResponse.json({
     version: AGENT_VERSION,
-    windows: `/edubox-agent-v${AGENT_VERSION}.exe`,
-    linux: `/edubox-agent-v${AGENT_VERSION}`,
-    mac: `/edubox-agent-v${AGENT_VERSION}-mac`,
+    windows: `/${AGENT_BIN_NAME}-v${AGENT_VERSION}.exe`,
+    linux: `/${AGENT_BIN_NAME}-v${AGENT_VERSION}`,
+    mac: `/${AGENT_BIN_NAME}-v${AGENT_VERSION}-mac`,
   });
 }

server/app/api/internal/send-to-node/route.ts

@@ -0,0 +1,12 @@
+import { NextRequest, NextResponse } from "next/server";
+import { sendToNode } from "@/lib/websocket";
+
+export async function POST(req: NextRequest) {
+  const body = await req.json();
+  const { nodeId, message } = body;
+  if (!nodeId || !message) {
+    return NextResponse.json({ error: "Missing nodeId or message" }, { status: 400 });
+  }
+  const sent = sendToNode(nodeId, message);
+  return NextResponse.json({ sent });
+}