Sova v0.3.3

Updates from inside Sova, project modes, reply timings and a faster chat open. 198 commits since
v0.3.2. The highlights:

• Sova updates itself. Settings → General has an Updates section: it says what runs, checks
  Sova's repository daily (or now, with Check Now), and upgrades in a job of its own; a dot on
  Settings says when an update is waiting. Upgrade automatically never reinstalls a version that was
  put back.
• Project minor modes. A project can ship its own minor modes; they show in the chat's mode
  menu and turn on after you approve the mode's folder. Workers get their parent's project mode
  tools.
• Reply timings. A measured reply shows a timing card on its head, and the Agents page has a
  Performance tab.
• Chats open at once. A chat opens on its saved rows while it starts, and opening a sleeping
  chat (or selecting its workspace tab) starts it. A quiet chat closes after its idle time even with
  a tab open.
• The changes viewer shows each step's commits, keeps empty steps greyed with their reason, and
  orders commits by history.
• Sidebar and Settings. The sidebar's search is always on, the Overseer button lists project
  overseers with their unread replies, and multi-select and the Profiles section are gone. In
  Settings, Cancel discards unsaved edits and closes; Discard Changes is gone.
• Resource monitor says clearly how much memory Sova uses, and the server holds less of it.

Going back to v0.3.2 (SOVA_REF=v0.3.2) hasn't been tested on this release: project mode
approvals, update settings and reply timings stay stored but unused.