chore: install shadcn skill

Signed-off-by: Dmytro Stanchiev <git@dmytros.dev>

.claude/skills/shadcn/agents/openai.yml

@@ -0,0 +1,5 @@
+interface:
+  display_name: "shadcn/ui"
+  short_description: "Manages shadcn/ui components — adding, searching, fixing, debugging, styling, and composing UI."
+  icon_small: "./assets/shadcn-small.png"
+  icon_large: "./assets/shadcn.png"