feat(cli): Peer Host HostInvoke parity, login TUI, and account sync

[bobleer]

Summary

• Add CLI Peer Device Mode host: Core-backed HostInvoke registry (workspace/config/session/dialog/git/snapshot rollback) with soft empty responses for Desktop-only surfaces (MiniApps/ACP/cron), so Desktop→CLI peer matches Desktop→Desktop for hydrate/chat/rollback flows.
• Add CLI login TUI and account sync panel (local vs cloud settings choice, device list, logout), plus shared same-machine device identity for Desktop/CLI AuthConnect election.
• Update peer-device-mode docs/specs and ignore local .tmp/ / tmp/ scratch dirs.

Test plan

• Rebuild CLI on Linux: cargo build -p bitfun-cli
• Login on CLI (/login), confirm sync choice / account page
• From Mac Desktop (same account), Peer Mode into the CLI host
• Open host workspace → create session → send message (no update_session_model / get_config unsupported errors)
• Rollback a turn on peer session (no rollback_to_turn unsupported error)
• Confirm MiniApps/ACP hydrate does not hard-fail (empty lists)