Prevent terminal output overflow resyncs

What's Changed

• Coalesce contiguous tiny PTY frames across server, client, and browser queues so item counts no longer trip before byte capacities.
• Use cancellable mthost IPC backpressure and transfer live WebSocket frame ownership so stalled sends cannot block terminal ingestion.
• Bound outstanding xterm parse work with timeout safety and identify the affected session and cause in overflow warnings.
• Cover tiny-frame bursts, blocked sends, cancellation, ordering, buffer cleanup, and xterm parse stalls with regression tests.

Release integrity

Native archives have matching platform-specific SPDX SBOM assets plus GitHub build-provenance and SBOM attestations. Installers and the built-in updater additionally verify a signed manifest and all packaged-file hashes.

Verification guide · Security policy