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/utils/immersive.ts

@@ -16,6 +16,10 @@
  * already does the right thing and these calls are no-ops.
  */
 
+import { createLogger } from "$lib/utils/logger";
+
+const log = createLogger("Immersive");
+
 interface AndroidImmersiveBridge {
   enter(): void;
   exit(): void;
@@ -38,7 +42,7 @@ export function isImmersiveSupported(): boolean {
   try {
     return bridge()?.isSupported() ?? false;
   } catch (err) {
-    console.warn("[Immersive] isSupported check failed:", err);
+    log.warn("isSupported check failed:", err);
     return false;
   }
 }
@@ -48,7 +52,7 @@ export function enterImmersive(): void {
   try {
     bridge()?.enter();
   } catch (err) {
-    console.error("[Immersive] Failed to hide the system bars:", err);
+    log.error("Failed to hide the system bars:", err);
   }
 }
 
@@ -63,6 +67,6 @@ export function exitImmersive(): void {
   try {
     bridge()?.exit();
   } catch (err) {
-    console.error("[Immersive] Failed to restore the system bars:", err);
+    log.error("Failed to restore the system bars:", err);
   }
 }