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/services/nextEpisodeService.ts

@@ -15,6 +15,9 @@ import { goto } from "$app/navigation";
 import { cancelAutoplayCountdown } from "$lib/api/autoplay";
 import { nextEpisode } from "$lib/stores/nextEpisode";
 import type { MediaItem } from "$lib/api/types";
+import { createLogger } from "$lib/utils/logger";
+
+const log = createLogger("NextEpisode");
 
 /** Guard against double-navigation */
 let isNavigating = false;
@@ -46,11 +49,11 @@ export async function cancelAutoPlay() {
  */
 function navigateToEpisode(episode: MediaItem) {
   if (isNavigating) {
-    console.warn("[NextEpisode] Already navigating, skipping duplicate navigation to", episode.id);
+    log.warn("Already navigating, skipping duplicate navigation to", episode.id);
     return;
   }
   isNavigating = true;
-  console.log("[NextEpisode] Navigating to next episode:", episode.id, episode.name);
+  log.debug("Navigating to next episode:", episode.id, episode.name);
   nextEpisode.hidePopup();
   goto(`/player/${episode.id}?restart=true`, { replaceState: true }).finally(() => {
     isNavigating = false;