feat(gui): redesign the Shared with Me page

Show only sections with content, invitations first, and an empty state
when nothing is shared. Rows drop the mount path from the subtitle, show
access as a tinted pill (Can view / Can edit / Can manage) and move
Open, Show in My Files and Leave into a menu. The invitations banner is
gone now that invitations lead the page.

docs/CHANGELOG.md

@@ -132,9 +132,13 @@ Schema: **31** (unchanged).
 - **New app icon.** A white cloud with the download arrow cut out of it, on a rounded Proton
   purple tile with a darker lower edge, drawn to the GNOME app-icon grid. It stays legible down to
   16 px on light and dark panels.
-- **Shared with Me.** Inside a shared folder the header shows the path from the share down, and a
-  back button in the header replaces the Back row. Pending invitations are announced in a banner
-  at the top of the page; Review scrolls to them.
+- **Shared with Me redesign.** Only sections with something in them are shown, and a page
+  with nothing shared says so in one place. Pending invitations sit at the top, with an Accept
+  button beside each. A row reads as the name over who shared it, when, and its size; what the
+  share allows is a tinted pill ("Can view", "Can edit", "Can manage") rather than a bare
+  role word that looked like a button. Open, Show in My Files and Leave… are in the row's ⋮
+  menu, and folders show a chevron. Inside a shared folder the header shows the path from the
+  share down, with a back button. Add Bookmark is an icon in the header.
 - **US spelling throughout.** The app, the CLI and the docs say "Favorite" and "color", matching the
   `pdfs favorite` command.