Preserve terminal replay through resize

What's Changed

• Fixed a terminal startup and update recovery deadlock: synchronous xterm resize flushes now preserve empty replay-barrier writes, their callbacks and following output instead of treating an empty string as the end of the queue.
• Applied the same empty-write handling to synchronous writes and rebuilt both distributed xterm bundles.
• Added regressions against the real xterm write buffer and public terminal bundle; verified ten forced resize/replay collisions in Chrome with retained history, completed callbacks and subsequent live output.

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