release: v1.1.0

[l-hellmann]

Changelog entry for v1.1.0. Merging this PR is the approval gate for the release — once it merges, the release skill resumes and cuts the GitHub Release on the new main HEAD.

[v1.1.0] - 2026-05-26

Added

• zcli upgrade command to update the CLI binary to the latest or a specific version; supports --check (report without installing), --version (pin target), --pick-version (interactive TUI picker), --include-pre-release (include pre-releases in the picker), --no-cache (skip cached check), and --download-timeout
• Background version-available warning shown on any command invocation when a newer version exists, with the result cached on disk to avoid per-invocation latency
• npm package now ships prebuilt per-platform binaries as optional dependencies, reducing install size

Changed

• upgrade --check exits non-zero when an update is available, enabling use in scripts