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/VideoDownloadButton.svelte

@@ -3,6 +3,9 @@
   import { auth } from "$lib/stores/auth";
   import { commands } from "$lib/api/bindings";
   import { QUALITY_PRESETS, type QualityPreset } from "$lib/api/quality-presets";
+  import { createLogger } from "$lib/utils/logger";
+
+  const log = createLogger("VideoDownloadButton");
 
   interface Props {
     itemId: string;
@@ -57,17 +60,17 @@
     try {
       const userId = $auth.user?.id;
       if (!userId) {
-        console.error("No user ID found");
+        log.error("No user ID found");
         return;
       }
 
       const repo = auth.getRepository();
 
-      console.log("🎬 Starting video download for item:", itemId, "quality:", quality);
+      log.debug("🎬 Starting video download for item:", itemId, "quality:", quality);
 
       // Get stream URL based on quality
       const streamUrl = await repo.getVideoDownloadUrl(itemId, quality);
-      console.log("   Stream URL obtained");
+      log.debug("   Stream URL obtained");
 
       // Get target directory
       const targetDir = await commands.storageGetPath();
@@ -85,7 +88,7 @@
         filePath = `videos/${safeName}.mp4`;
       }
 
-      console.log("   File path:", filePath);
+      log.debug("   File path:", filePath);
 
       // Queue download with video metadata
       const downloadId = await downloads.downloadVideo(
@@ -101,16 +104,16 @@
         episodeNumber,
         seasonNumber
       );
-      console.log("   Download queued with ID:", downloadId);
+      log.debug("   Download queued with ID:", downloadId);
 
       // Pin the item metadata
       await downloads.pinItem(itemId);
 
       // Actually start the download
       await commands.startDownload(downloadId, streamUrl, targetDir);
-      console.log("   Download started");
+      log.debug("   Download started");
     } catch (error) {
-      console.error("Failed to start video download:", error);
+      log.error("Failed to start video download:", error);
     } finally {
       isProcessing = false;
     }