stream request bodies through the photos sidecar

both forwarders buffered the whole request body into an ArrayBuffer before
re-sending it to Immich. with maxRequestBodySize at 4GB that put a phone's
video upload in the sidecar's heap for a hop that never reads the bytes.

callUpstream now sets duplex: 'half' so a stream is a legal body, matching
what createSidecarProxy already does on the platform side. the four JSON
callers are unaffected.

the platform proxy forwards no content-length, so the body already reached
us chunked; this extends that one hop to Immich. verified against the live
instance (3.1.0): bulk-upload-check round-trips a streamed body and returns
the right verdict.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/servers/sidecar/photos/locked.ts

@@ -268,7 +268,8 @@ async function forward(req: Request, url: URL, cfg: UpstreamConfig, userId: numb
     path: `/api/${rest}`,
     method: req.method,
     query: search ? `?${search}` : '',
-    body: hasBody ? await req.arrayBuffer() : null,
+    // Streamed, not buffered — same reason as the unlocked forwarder in routes.ts.
+    body: hasBody ? req.body : null,
     contentType: req.headers.get('content-type'),
     range: req.headers.get('range'),
     ifNoneMatch: req.headers.get('if-none-match'),