refactor(logging): route frontend console calls through the logger

TRACES: | DR-204

484 ungated `console.*` calls across 63 non-test frontend files shipped to
end users with no way to turn them off. Mechanical substitution, no control
flow, error handling or message semantics changed:

  console.log / console.debug -> log.debug
  console.info                -> log.info
  console.warn                -> log.warn
  console.error               -> log.error

Hand-written `"[Scope] …"` prefixes are dropped where the logger's scope
now carries them; scope names that already existed are preserved verbatim
(`[Auth]`, `[VideoPlayer]`, `[PiP]`, …) and inferred from the filename
where a file had none. `src/routes/player/[id]/+page.svelte` keeps its
`NextEpisode` and `AutoPlay` sub-scopes as separate loggers rather than
flattening them into the page scope.

`grep -rn 'console\.' src/` now matches nothing outside the tests and the
facade itself.

src/lib/components/library/AlbumDownloadButton.svelte

@@ -2,6 +2,9 @@
   import { downloads } from "$lib/stores/downloads";
   import { auth } from "$lib/stores/auth";
   import type { MediaItem } from "$lib/api/types";
+  import { createLogger } from "$lib/utils/logger";
+
+  const log = createLogger("AlbumDownloadButton");
 
   interface Props {
     albumId: string;
@@ -60,7 +63,7 @@
     try {
       const userId = $auth.user?.id;
       if (!userId) {
-        console.error("No user ID found");
+        log.error("No user ID found");
         return;
       }
 
@@ -95,7 +98,7 @@
         await downloads.refresh(userId);
       }
     } catch (error) {
-      console.error("Album download operation failed:", error);
+      log.error("Album download operation failed:", error);
     } finally {
       isProcessing = false;
     }