fix(search): the live-search tooltip says what a search costs

It always said a live search spends the shared API quota, while the default source (the website's
own endpoint, scrape) spends none — the owner avoided a free search because of it. /api/me now names
the running search_source, and the tooltip names the cost under it: none for scrape (the enrich step
costs a unit or two), 100 units a page for the official API.

frontend/src/lib/api/account.ts

@@ -20,6 +20,7 @@ export interface Me {
   has_password: boolean;
   google_enabled: boolean;
   plex_enabled: boolean;
+  search_source: "scrape" | "api";
   can_read: boolean;
   can_write: boolean;
   pending_invites: number;