fix(hub): raise maxRequestBodySize so file uploads work (#397)

* fix(hub): raise maxRequestBodySize so file uploads work

The Bun server inherited maxRequestBodySize from Socket.IO's default
maxHttpBufferSize (1 MB).  The upload endpoint sends files as base64
in JSON, so any image > ~750 KB was silently rejected before reaching
the route handler.  The frontend allows 50 MB uploads.

Raise the limit to at least 100 MB to accommodate 50 MB files with
base64 encoding overhead (~33%).

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Co-Authored-By: HAPI <noreply@hapi.run>

* fix(hub,web): fix file uploads — raise body limit, lower max size, show errors

Three changes:

1. hub/server.ts: Bun's maxRequestBodySize inherited Socket.IO's 1 MB
   default, silently rejecting any upload. Raise to 10 MB.

2. hub/routes + web/attachmentAdapter: lower MAX_UPLOAD_BYTES from
   50 MB to 5 MB (realistic for images; 5 MB base64 ≈ 6.7 MB body,
   fits within the 10 MB server limit).

3. web/AttachmentItem: show "Upload failed" text and strike-through
   filename on error, instead of just a tiny icon.

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Co-Authored-By: HAPI <noreply@hapi.run>

* fix(hub): keep 50MB upload limit, size maxRequestBodySize to match

Bot review correctly flagged that lowering MAX_UPLOAD_BYTES to 5 MB
regresses the documented 50 MB limit. Revert to 50 MB and calculate
maxRequestBodySize properly: 50 MB × 4/3 (base64) + 1 MB (JSON
overhead) ≈ 68 MB.

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <noreply@hapi.run>

---------

Co-authored-by: HAPI <noreply@hapi.run>

hub/src/web/server.ts

@@ -234,7 +234,7 @@ export async function startWebServer(options: {
         hostname: configuration.listenHost,
         port: configuration.listenPort,
         idleTimeout: Math.max(30, socketHandler.idleTimeout),
-        maxRequestBodySize: socketHandler.maxRequestBodySize,
+        maxRequestBodySize: Math.max(socketHandler.maxRequestBodySize, 68 * 1024 * 1024),
         websocket: socketHandler.websocket,
         fetch: (req, server) => {
             const url = new URL(req.url)

web/src/components/AssistantChat/AttachmentItem.tsx

@@ -43,7 +43,8 @@ export function AttachmentItem() {
                     <ErrorIcon />
                 </span>
             ) : null}
-            <span className="max-w-[150px] truncate">{name}</span>
+            <span className={`max-w-[150px] truncate ${isError ? 'text-red-500 line-through' : ''}`}>{name}</span>
+            {isError ? <span className="text-xs text-red-500 whitespace-nowrap">Upload failed</span> : null}
             <AttachmentPrimitive.Remove
                 className="ml-auto flex h-5 w-5 items-center justify-center rounded text-[var(--app-hint)] transition-colors hover:text-[var(--app-fg)]"
                 aria-label="Remove attachment"