testing/cross_backend/testing_server_bun.ts

Bun runtime adapter for spawnable cross-process test server binaries.

Binds Bun.serve and hono/bun's module-level upgradeWebSocket + websocket handler. The shared testing/cross_backend/testing_server_core.ts owns the rest. Third sibling to testing/cross_backend/testing_server_node.ts / testing/cross_backend/testing_server_deno.ts — together the three isolate the JS-runtime axis (Node V8 / Deno V8 / Bun JSC) on identical TS surfaces, and the Rust spine binary covers the cross-language axis.

Needs no extra deps: hono/bun ships with the hono peer dep and Bun.serve is built in (unlike Node, which pulls @hono/node-server + @hono/node-ws). RuntimeDeps reuse create_node_runtime — Bun implements the node:fs / node:process surface RuntimeDeps + cli/daemon touch.

Bun.serve is declared locally (mirroring testing/cross_backend/testing_server_deno.ts's Deno declaration) so this module typechecks under fuz_app's Node-based config without @types/bun. It is only ever *run* under Bun.