v1.3.0

This release tightens how monitors are created and configured, and documents the
profile model.

Monitors and profiles

• A monitor now requires at least one profile. The profiles relationship is the
  monitor_profile_map join table, not a column on monitors, so nothing
  stopped a monitor from being created with none. Such a monitor started, found
  nothing to dispatch to and exited, which the CLI reported as "started" and the
  web GUI as an unexplained startup failure. The CLI and the web GUI now enforce
  the rule on create, edit and start, monitor test reports missing profiles
  instead of passing with nothing tested, and a scheduled monitor fails the start
  like an instant monitor rather than silently idling.
• The remote path is now conditional on the linked profiles. A remote profile
  copies files between the monitor path and the remote path; a command profile
  runs a command and never touches it. Both interfaces now pick the profiles
  first and ask for the remote path afterwards: the CLI prompts for it only when
  a remote profile was selected, and the GUI labels it accordingly (the profile
  picker, name and monitor path moved outside the Streamlit form so the label
  updates live). A remote path left over from an earlier remote profile is kept
  rather than cleared, so re-linking a remote profile does not mean re-entering
  it. A monitor that has a remote profile but no remote path is refused at start,
  and a NULL remote path is normalised to an empty string when read.

Documentation

• New profiles guide covering the profile model, the profile properties and the
  two profile categories (remote and command).
• New web GUI getting-started page with screenshots of a profile form, the
  monitor wizard, the monitor list and a monitor log.
• Updated the monitors guide for the "at least one profile" rule and the
  conditional remote path.

Continuous integration

• The unit tests run on every pull request and every push to main
  (.github/workflows/test.yml), through the same make test-unit target a
  developer runs locally, so CI cannot drift away from it.
• The unit tests no longer depend on local fixtures or a local rclone install.
• The GitHub Release body is generated from the matching CHANGELOG.md section
  by utils/release_notes.py. A tagged build fails when the tag, version.py
  and the changelog disagree, so a mis-tagged release cannot publish the wrong
  notes.
• Workflow actions bumped to actions/checkout@v7 and
  actions/setup-python@v7.

The database schema is unchanged (1.0.0), so mhub database upgrade is not
required for this release.