feat: add bun-fullstack agent and update skills

.agent/skills/tech-stack/elysiajs/examples/basic.ts

@@ -0,0 +1,9 @@
+import { Elysia, t } from 'elysia'
+
+new Elysia()
+	.get('/', 'Hello Elysia')
+	.post('/', ({ body: { name } }) => name, {
+		body: t.Object({
+			name: t.String()
+		})
+	})