v0.30.3: say what a project is, and the filing check listens

• Why. soul-pool, the pool-playing agent, still showed Poise decisions: the filing check judged projects by sample
  note titles, and soul-pool's samples were the polluted imports themselves.
• One line per project. Each project page takes a short description (click under the title): "the pool-playing
  agent". The filing check treats it as the owner's word on what belongs there, ahead of sample titles.
• A way out. A note that clearly does not fit its project's description, and fits no other listed project, is
  proposed for Unsorted (a folder, not a project) instead of staying put.
• For agents: nothing changes.