Add repository metadata and package AI skill

skills/crypstie/agents/openai.yaml

@@ -0,0 +1,4 @@
+interface:
+  display_name: "Crypstie"
+  short_description: "Create and open encrypted Crypstie links"
+  default_prompt: "Use $crypstie to securely create or open a Crypstie link."