feat(agent): v0.3.9 sync, UI details, self-update, centralized version

- Add agent/server startup sync (sync/sync_response)
- Centralize agent version in agent/VERSION + expose /api/agent/version
- Display agent version, nodeId and server version in local UI
- Add agent self-update detection/download/restart via helper scripts
- Run start/stop/delete/reset handlers in goroutines to avoid WebSocket blocking
- Update dashboard download links and SUIVI_VPN_ONDEMAND.md
- Document Podman stays installer-managed, not agent-updated

server/lib/websocket.ts

@@ -3,6 +3,7 @@ import { randomBytes } from "crypto";
 import type { IncomingMessage } from "http";
 import { prisma } from "./prisma";
 import { createEphemeralPreAuthKey, getHeadscaleUserId } from "./headscale";
+import { getAgentVersion } from "./agent-version";
 
 interface NodeMessage {
   action: string;
@@ -12,10 +13,16 @@ interface NodeMessage {
   type?: string;
   port?: number;
   composeConfig?: string;
+  initScript?: string;
   studentName?: string;
   error?: string;
   tailscaleIp?: string;
   token?: string;
+  serverVersion?: string;
+  instances?: Array<{ id: string; status: string; port: number; templateName?: string }>;
+  toStart?: Array<{ id: string; type: string; port: number; composeConfig?: string; initScript?: string }>;
+  toDelete?: string[];
+  toStop?: string[];
 }
 
 const nodes = new Map<string, WebSocket>();
@@ -126,7 +133,7 @@ export function initWebSocketServer(wss: WebSocketServer) {
               create: { id, status: "online", lastSeen: new Date() },
             });
           }
-          ws.send(JSON.stringify({ action: "registered" }));
+          ws.send(JSON.stringify({ action: "registered", serverVersion: getAgentVersion() }));
           return;
         }
 
@@ -263,6 +270,58 @@ export function initWebSocketServer(wss: WebSocketServer) {
           return;
         }
 
+        if (msg.action === "sync" && msg.instances) {
+          const serverInstances = await prisma.instance.findMany({
+            where: { nodeId },
+            include: { template: true },
+          });
+
+          const localIds = new Set(msg.instances.map((i) => i.id));
+          const serverIds = new Set(serverInstances.map((i) => i.id));
+
+          const toDelete = msg.instances
+            .filter((i) => !serverIds.has(i.id))
+            .map((i) => i.id);
+
+          const toStop = msg.instances
+            .filter((i) => {
+              const server = serverInstances.find((s) => s.id === i.id);
+              return server && server.status === "stopped" && i.status === "running";
+            })
+            .map((i) => i.id);
+
+          const toStart = serverInstances
+            .filter((s) => !localIds.has(s.id))
+            .map((s) => ({
+              id: s.id,
+              type: s.template.type,
+              port: s.port,
+              composeConfig: s.template.composeConfig,
+              initScript: s.template.initScript ?? undefined,
+            }));
+
+          console.log(
+            "[WS] Sync for",
+            nodeId,
+            "- toStart:",
+            toStart.length,
+            "toDelete:",
+            toDelete.length,
+            "toStop:",
+            toStop.length
+          );
+
+          ws.send(
+            JSON.stringify({
+              action: "sync_response",
+              toStart,
+              toDelete,
+              toStop,
+            })
+          );
+          return;
+        }
+
         if (msg.action === "instance_started" && msg.instanceId) {
           const { count } = await prisma.instance.updateMany({
             where: { id: msg.instanceId },