v0.1.1 - Better SSH

Identities, hardware keys, install, and the terminal workspace after v0.1.0.

• Identities, then the agent. Files from the profile (or OpenSSH's default
  id_ed25519 / id_ecdsa / id_rsa when none are set) are offered in order,
  then the local agent unless IdentitiesOnly is set. There is no
  agent-versus-key radio. A missing User is the local account. HostKeyAlias
  is the known-hosts lookup name; TCP still uses HostName. Encrypted files and
  unsupported agent algorithms are named in the error (the SSH agent holds 3 keys, 1 unsupported (sk-ecdsa-…)).
• Agent-held sk-ssh-ed25519. Hardware keys in the local agent are offered;
  signing stays in the authenticator. sk-ecdsa and file-based SK keys are not.
• Saved workspace. Restored tabs re-read identity policy and blockers from
  ~/.ssh/config. An unreadable workspace.conf is a system dialog before the
  window opens: clear the file, or exit and leave it.
• Desktop. Maximize is tmux zoom and keeps focus. Exit returns to the form
  and retitles the tab from those fields. Alternate-screen panes and a History
  setting below tmux's buffer are not warned as lost output. After keys or
  wheel, remote echo runs at 20 fps for a short time. Wheel ticks are one per
  40 points; leftover smoothing cannot add extra ticks.
• Install. make install does not assume GNU install -D. On macOS it
  writes ~/Applications/Starcom.app. macOS/Windows icons use a full PNG
  family for cargo-bundle --bin.

Prebuilt Linux, macOS, and Windows artifacts are attached below. Linux and
Windows builds are unsigned; macOS builds are ad-hoc codesigned, not notarized.

Known limitations: MFA, host and user certificates, ProxyJump, ProxyCommand,
sk-ecdsa and file-based SK keys, and reusing one SSH connection across tabs
are not supported. Remote hosts are Linux with stock OpenSSH and tmux. No
performance baselines are published yet.