feat(settings): rebuild reader fonts on the shared font ledger

Reader › Fonts now uses the Server Fonts ledger, family sheet and upload tray for a reader's own
fonts, and lists the server's fonts with a show/hide switch and a preview sheet. The shared pieces
move to features/settings/fonts and the ledger columns narrow to give the specimen room.
Server: additive GET /fonts/usage and PATCH /fonts/families, upload error codes, and a 409 instead
of a 500 when a reader uploads a second file for the same face.

server/test/e2e/authorization-matrix/route-inventory/uncovered-routes.json

@@ -83,6 +83,7 @@
   "GET /dashboard/widgets/year-projection",
   "GET /fonts",
   "GET /fonts/:id/file",
+  "GET /fonts/usage",
   "GET /hardcover/books",
   "GET /hardcover/books/:bookId/editions",
   "GET /hardcover/books/:bookId/sync-state",
@@ -162,6 +163,7 @@
   "PATCH /custom-metadata/fields/:id",
   "PATCH /custom-metadata/fields/reorder",
   "PATCH /fonts/:id",
+  "PATCH /fonts/families",
   "PATCH /hardcover/books/:bookId/edition",
   "PATCH /hardcover/books/:bookId/sync-state",
   "PATCH /hardcover/settings",