v0.6.0: per-artifact actions menu (⋯ + right-click)

A ⋯ button on row hover and right-click on a feed row open the same floating
menu: Keep / Open / Copy link / Delete. Dismisses on click-away/Escape,
edge-flips to stay on-screen. Standalone one-click Delete icon stays; the
Trash view keeps its dedicated Undelete.

- Row markup: actions grouped in a .row-actions container (delete + ⋯ in the
  feed/keep views; undelete in trash). Reuses the existing keep endpoint.
- Menu only in the normal/keep views, not trash. Keep-toggle syncs the row's
  kept badge + the preview Keep button, and (in the Keep folder) drops the row
  when unkept.
- Frontend-only (no backend change); inline JS validated with node --check;
  152 tests pass; feed renders in all views.

Share + Add-label join the menu in later slices.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

daybook_project/__init__.py

@@ -1,4 +1,4 @@
 # Single source of truth for the app version. Bump this, commit, then tag the
 # commit `vX.Y.Z` and deploy. Surfaced on Settings -> About and in
 # GET /api/capabilities ("version").
-__version__ = "0.5.1"
+__version__ = "0.6.0"