feat: add bun-fullstack agent and update skills

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

@@ -0,0 +1,38 @@
+import { Elysia, t } from 'elysia'
+
+class CustomError extends Error {
+	constructor(public name: string) {
+		super(name)
+	}
+}
+
+new Elysia()
+	.error({
+		CUSTOM_ERROR: CustomError
+	})
+	// global handler
+	.onError(({ code, error, status }) => {
+		switch (code) {
+			case "CUSTOM_ERROR":
+				return status(401, { message: error.message })
+
+			case "NOT_FOUND":
+				return "Not found :("
+		}
+	})
+	.post('/', ({ body }) => body, {
+		body: t.Object({
+			username: t.String(),
+			password: t.String(),
+			nested: t.Optional(
+				t.Object({
+					hi: t.String()
+				})
+			)
+		}),
+		// local handler
+		error({ error }) {
+			console.log(error)
+		}
+	})
+	.listen(3000)