Add job presets

[floriandejonckheere]

Summary

Adds presets: sets of recommended rsync options for common use cases, defined in JobPreset (app/objects/job_preset.rb).

• Job form: a new "Preset" card with a dropdown. Selecting a preset asks for confirmation (the basic, advanced and custom rsync options will be overwritten) and then updates the toggles, linked options (archive/delete) and command preview. Cancelling restores the previous selection.
• Job wizard: a new "Preset" step before "Schedule & options". The selected preset pre-fills the options, which can still be changed in the next step.
• Presets: Borg repository, Restic repository, exact mirror, archive (never delete), VM images and large files, keep previous versions, slow or unreliable network, and trial run.
  • Applying a preset resets all toggles to their defaults, enables the preset's options and replaces the custom rsync arguments. Rsync paths, SSH arguments and include/exclude patterns are left untouched.
  • The trial run preset is additive: it only enables --dry-run --itemize-changes and keeps the other options.
• Development: init: true in compose.yml. Foreman ran as PID 1 and shut the container down whenever an orphaned process (e.g. Chrome spawned by system specs run via docker compose exec) exited.

Not included (tracked in docs/PROJECT.md): the Borg lock-check pre-hook (needs a {source_path} hook variable and only works for local sources), and dated --backup-dir directories for the previous versions preset.

Testing

• bundle exec rspec and bundle exec rspec spec/system (new: spec/objects/job_preset_spec.rb, spec/system/jobs/presets_spec.rb, preset step in spec/requests/job_wizards_request_spec.rb)
• Recreate the dev containers (docker compose up -d app worker) to pick up init: true
• Manually: edit a job, pick a preset, confirm/cancel the dialog; create a job through the wizard with and without a preset