* fix(files): keep large downloads connected
Large file reads were emitted as one frame, crossing the physical socket high-water mark and terminating otherwise healthy connections. Stream bounded chunks from one file handle and pace each transfer by its own send completion without globally queueing unrelated traffic.
* fix(files): keep paced relay transfers bounded
Carry send completion through encryption to the physical WebSocket callback, cap growing files at their advertised size, and preserve text classification when a UTF-8 code point crosses the sample boundary.
* fix(files): reject changing transfer snapshots
Abort when a file shrinks below its advertised size, finalize UTF-8 validation for complete samples, and let the physical relay socket remain the sole authority for queued-byte accounting.
* fix(files): validate metadata before transfer
Keep the daemon handshake pending until the ready frame is physically sent, and classify file content with a bounded full-handle scan so streaming preserves the previous binary/text behavior.
* fix(files): detect changing transfer sources
* fix(files): enforce transfer snapshot integrity
