feat: add webchat pwa push subscription support

src/config/schema.ts

@@ -79,6 +79,15 @@ const serverDiscoverySchema = z.object({
   txt: z.record(z.string(), z.string()).default({}),
 }).default({});
 
+const serverWebchatPushSchema = z.object({
+  /** Enable WebChat web-push subscription endpoints and PWA metadata. */
+  enabled: z.boolean().default(false),
+  /** VAPID public key used by browser PushManager.subscribe(). */
+  vapid_public_key: z.string().optional(),
+  /** Soft cap for stored web-push subscriptions. */
+  max_subscriptions: z.number().min(1).max(50_000).default(5000),
+}).default({});
+
 const serverNodePolicySchema = z.object({
   /** Enable node registration/capability RPC surface. */
   enabled: z.boolean().default(false),
@@ -118,6 +127,8 @@ const serverSchema = z.object({
   queue: laneQueueSchema,
   /** Optional companion-node registration/capability settings. */
   nodes: serverNodePolicySchema,
+  /** Optional WebChat PWA push-subscription settings. */
+  webchat_push: serverWebchatPushSchema,
   /** Optional Bonjour/mDNS advertisement settings. */
   discovery: serverDiscoverySchema,
 });