Add unified captcha third-party services skill with official API workflow

captcha-third-party-services/agents/openai.yaml

@@ -0,0 +1,4 @@
+interface:
+  display_name: "Captcha Third-Party Services"
+  short_description: "Unified workflows for 2Captcha, YesCaptcha, Anti-Captcha"
+  default_prompt: "Use official APIs to create captcha tasks, poll results, and manage provider fallback across 2Captcha, YesCaptcha, and Anti-Captcha."