fix: declare case-status webhook endpoint in manifest

Add webhooks[] array to plugin.json and manifest.ts with the
'case-status' endpointKey. Without this declaration, Paperclip
registers 0 webhooks even when onWebhook() is implemented, so
POST /api/plugins/marcusgroup.legal-ai/webhooks/case-status would
return 501 and never reach the handler.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/manifest.ts

@@ -159,4 +159,12 @@ export default {
 			schedule: "*/15 * * * *",
 		},
 	],
+	webhooks: [
+		{
+			endpointKey: "case-status",
+			displayName: "עדכון סטטוס תיק",
+			description:
+				"מקבל עדכוני סטטוס מ-legal-ai ומפרסם תגובה על ה-issue המקושר",
+		},
+	],
 };