## Summary
Fix a memory leak in `RequestContext.doRenderWithBody()` where
`Strong.Impl` memory was leaked when proxying streaming responses
through Bun's HTTP server.
## Problem
When a streaming response (e.g., from a proxied fetch request) was
forwarded through Bun's server:
1. `response_body_readable_stream_ref` was initialized at line 1836
(from `lock.readable`) or line 1841 (via `Strong.init()`)
2. For `.Bytes` streams with `has_received_last_chunk=false`, a **new**
Strong reference was created at line 1902
3. The old Strong reference was **never deinit'd**, causing
`Strong.Impl` memory to leak
This leak accumulated over time with every streaming response proxied
through the server.
## Solution
Add `this.response_body_readable_stream_ref.deinit()` before creating
the new Strong reference. This is safe because:
- `stream` exists as a stack-local variable
- JSC's conservative GC tracks stack-local JSValues
- No GC can occur between consecutive synchronous Zig statements
- Therefore, `stream` won't be collected between `deinit()` and
`Strong.init()`
## Test
Added `test/js/web/fetch/server-response-stream-leak.test.ts` which:
- Creates a backend server that returns delayed streaming responses
- Creates a proxy server that forwards the streaming responses
- Makes 200 requests and checks that ReadableStream objects don't
accumulate
- Fails on system Bun v1.3.5 (202 leaked), passes with the fix
## Related
Similar to the Strong reference leak fixes in:
- #23313 (fetch memory leak)
- #25846 (fetch cyclic reference leak)
461ad886bd
