- re-scoped to OUTBOUND streaming only
- three decisions: separate StreamHandler/BodyProducer parallel path (Resp
path untouched -> existing responses byte-identical); streaming routes opt
out of the after-chain, framework refuses at registration to combine with
header-mutating middleware (loud, never silent), security_headers() helper
lets handlers stamp them; chunked REQUEST bodies split into their own future
iteration (parse.wo refusal stays, smuggling cases enumerated for later)
- no language enhancement (net.write framing, fs.read_at/actor source,
interfaces for producer); rides the fiber loop not the actor pool, so not
lang-41-exposed
- fixed title inconsistency: "three iterations wait on" -> "two" (7 and 8)
- validated against .dev/reference/fiber + the app.wo/serve.wo pipeline. Board synced
(cherry picked from commit 15205408e03c3c02a38e00e5d2017a8a11f62f28)