Spynel 0.12.0

• Persist command, extension, prompt-preparation, and harness-start errors in conversation history. TUI Err messages for these failures survive restart and resume and appear in subsequent agent context. Command replies and model/harness selection confirmations are saved too.
• Correct job state after recovery admission, preserve the public job number, and fence late events from the previous execution.
• Fix Linux automatic startup units rejected with bad-setting. Preserve spaces, Unicode, quotes, backslashes, dollar signs, and percent signs in supported paths; reject control characters in workspace paths.
• Add standalone native installation and validated complete-bundle updates through install.sh and /update install, with stable restart/startup paths and retained previous bundles.

Existing broken Linux startup registrations must be regenerated after updating: toggle startup off and on, then run systemctl daemon-reload before starting the exact service name. Use systemctl --user for user registrations; root registrations live under /etc/systemd/system/.

Local validation passed: complete Go tests and vet (including the pinned Bubble Tea module), build, smoke/DOX, targeted race suites, npm checks, and Linux arm64 packaged installation/update/restart checks. Release verification and native package/harness checks passed on Linux amd64/arm64 and macOS amd64/arm64. All four archives, checksums, and npm 0.12.0 are published.