fix(docsync): name the store of a binding whose provider is switched off

Both shells keep a binding on screen after an admin switches its
provider off, and name its store through storeName(), which falls back
to a providerName on the link before the raw id. The server never sent
one, so such a binding was labelled with the provider id. publicLink
now carries providerName from document_providers.name whatever its
enabled flag, and every route and the MCP listing that return links go
through it.

The comments on docsync:changed in the realtime schema and the client's
event policy say that the event now also marks a binding created or
removed, and that the Files screen re-asks whether to offer the sync
button when it arrives.

client/src/api/wsEventPolicy.ts

@@ -82,8 +82,10 @@ export const HANDLED_OUTSIDE_TRIP_STORE = [
   'journey:book:peers',
   'journey:book:cursor',
   // Document sync: components/Files/docsync/useDocSync re-reads the bindings
-  // and their counts. Content-free like the bag ping: what a run changed is
-  // per-binding server state, and the files it moved arrive as file:* events.
+  // and their counts, and components/Files/docsync/useDocSyncOffered asks
+  // again whether the Files screen offers the sync button. Content-free like
+  // the bag ping: what a run changed is per-binding server state, and the
+  // files it moved arrive as file:* events.
   'docsync:changed',
   // Booking import — BackgroundTasks/BackgroundTasksWidget ('import:' prefix listener)
   'import:progress',