fix(frontend): stream dynamic response compression

[jomcgi]

Dynamic response compression buffered each complete upstream body before returning it. Concurrent large API/SSR responses therefore retained additional complete buffers alongside the upstream payloads, creating a demonstrated memory amplification risk under the public frontend's 384 MiB limit.

Stream through Node's gzip/Brotli compressors with byte-bounded output buffering and backpressure. Pipeline teardown cancels the upstream source when the downstream reader disconnects and propagates source errors to the reader. Remove content-length on streamed compressed responses. Keep HEAD, SSE, already encoded, non-text, bodyless, and known-small responses unchanged. Unknown-length small bodies are now compressed without first buffering them to determine size.

Validation: 44 hook tests pass on Node 22.16.0, including gzip/Brotli round trips, returning before the whole upstream is consumed, cancellation, source errors, exclusions, and existing cache/privacy contracts. The two upstream-consumption tests fail against the original hook. A synthetic 32-concurrent-response probe using 3.4 MB payloads measured peak RSS of 336 MiB before and 276 MiB after on Node 22.16.0. This is a local memory-risk reproduction, not proof of the production OOM cause or production capacity.

No resource limits, budgets, credentials, or permissions changed. Full repository CI and live rollout verification remain pending; the coordinating thread owns merging. Both monolith and monolith-public use this frontend hook.

[jomcgi]

Helm Manifest Diff

No manifest changes detected across 17 application(s).