fix: Bug - Sending files and attachment issues (gallery load and speed)

Route small images through in-memory receive instead of serialized disk
chunk-acks, and improve gallery hydration for local copies and pending
downloads so thumbnails display without minutes-long progress stalls.

Co-authored-by: Cursor <cursoragent@cursor.com>

toju-app/src/app/domains/attachment/domain/logic/attachment-serve.rules.ts

@@ -0,0 +1,4 @@
+/** True when a resolved on-disk path contains bytes worth streaming to a peer. */
+export function shouldServeAttachmentFromDiskPath(fileSize: number | null | undefined): boolean {
+  return typeof fileSize === 'number' && Number.isFinite(fileSize) && fileSize > 0;
+}