Unify daemon workspaces and settings

[winetree94]

What changed

• Replace the daemon-first startup flow with a unified workspace shell.
• Combine online daemon catalogs into a Host → Workspace → Worktree tree.
• Add per-worktree session tabs and integrated Provider/Daemon settings.
• Introduce protocol v5 worktree DTOs and typed RPCs.
• Add safe Git worktree creation, refresh, archive preview, and archive behavior.
• Persist multi-host profiles, credentials, workspace selection, and local tab state.

Why

The previous host-scoped, three-pane layout exposed daemon topology as the primary user experience. This follows the Paseo repository/worktree/session model while preserving independent daemon ownership and reconnection.

Validation

• dart run melos verify
• dart run melos verify:debug using the real Linux Debug runner
• Linux Debug build
• Android Debug APK build
• coder_app: 91.9% line / 80.9% branch
• coder_daemon: 90.4% line / 83.8% branch