feat(metadata): add external HTTP metadata providers

Register book-metadata-provider services by address, with no code change per
provider; Settings lists ready-made ones to install. Ranking prefers a record of
the book's own medium. LubimyCzytac moves out to its own provider and Aladin,
whose API closes, is retired; their ids stay. Adds migrations 0129 and 0130.
See docs/METADATA_PROVIDERS.md.

Ref #1405

server/test/e2e/authorization-matrix/route-inventory/manifest.json

@@ -1,8 +1,8 @@
 {
-  "totalRoutes": 704,
+  "totalRoutes": 711,
   "byPermission": {
-    "(none)": 297,
-    "Permission.ManageMetadataConfig": 41,
+    "(none)": 298,
+    "Permission.ManageMetadataConfig": 47,
     "Permission.EmailSend": 34,
     "Permission.LibraryEditMetadata": 54,
     "Permission.BookDockAccess": 17,