style(frontend): Prettier config + one-time repo-wide format pass

Prettier 3 (pinned), printWidth 100, double quotes — chosen to match the existing
hand-formatting and minimise reflow. This commit is ONLY the mechanical format pass
(`prettier --write`) plus the config/ignore/scripts, isolated so it never pollutes a
feature diff. Verified behaviour-neutral: typecheck, eslint (0 errors), and vitest
all green before and after. See .git-blame-ignore-revs — `git blame` skips this sha.

frontend/src/lib/notifications.ts

@@ -107,7 +107,9 @@ export function configureNotifications(p: Partial<NotifSettings>): void {
 let audioCtx: AudioContext | null = null;
 function beep(): void {
   try {
-    const Ctx = window.AudioContext || (window as unknown as { webkitAudioContext: typeof AudioContext }).webkitAudioContext;
+    const Ctx =
+      window.AudioContext ||
+      (window as unknown as { webkitAudioContext: typeof AudioContext }).webkitAudioContext;
     audioCtx = audioCtx || new Ctx();
     if (audioCtx.state === "suspended") void audioCtx.resume();
     const osc = audioCtx.createOscillator();
@@ -143,7 +145,13 @@ function load(): Notification[] {
     // live `action` callback, which can't survive serialization.
     return raw.map(
       (n) =>
-        ({ repeat: 1, ...(n as object), action: undefined, dismissed: true, transient: false }) as Notification
+        ({
+          repeat: 1,
+          ...(n as object),
+          action: undefined,
+          dismissed: true,
+          transient: false,
+        }) as Notification,
     );
   } catch {
     return [];
@@ -202,13 +210,14 @@ export function notify(input: NotifyInput): number {
   // config.durationMs === 0 means "don't auto-dismiss" (toast stays until dismissed).
   // A transient status stays put until its producer clears it (no auto-dismiss timer),
   // same as an interaction-awaiting notice.
-  const duration = requiresInteraction || input.transient
-    ? undefined
-    : level === "error" || level === "fatal"
-      ? ERROR_TTL
-      : config.durationMs > 0
-        ? config.durationMs
-        : undefined;
+  const duration =
+    requiresInteraction || input.transient
+      ? undefined
+      : level === "error" || level === "fatal"
+        ? ERROR_TTL
+        : config.durationMs > 0
+          ? config.durationMs
+          : undefined;
 
   // Coalesce a rapid burst of identical notifications (same level+title+message within the
   // window) into one entry with a bumped repeat count, instead of appending a fresh copy each
@@ -224,14 +233,14 @@ export function notify(input: NotifyInput): number {
         now - n.ts <= COALESCE_WINDOW_MS &&
         n.level === level &&
         (n.title ?? "") === (input.title ?? "") &&
-        n.message === input.message
+        n.message === input.message,
     );
     if (prior) {
       // Re-surface the existing toast (undismiss + unread) and re-arm its auto-dismiss timer.
       items = items.map((n) =>
         n.id === prior.id
           ? { ...n, ts: now, repeat: n.repeat + 1, dismissed: false, read: false, duration }
-          : n
+          : n,
       );
       emit();
       if (duration) setTimeout(() => dismiss(prior.id), duration);
@@ -260,7 +269,10 @@ export function notify(input: NotifyInput): number {
     },
   ];
   emit();
-  if (config.sound && (input.sound || requiresInteraction || level === "error" || level === "fatal")) {
+  if (
+    config.sound &&
+    (input.sound || requiresInteraction || level === "error" || level === "fatal")
+  ) {
     beep();
   }
   if (duration) setTimeout(() => dismiss(id), duration);
@@ -301,7 +313,7 @@ export function resolveVideo(videoId: string): void {
       !(
         (n.meta?.kind === "video-hidden" || n.meta?.kind === "video-watched") &&
         n.meta.videoId === videoId
-      )
+      ),
   );
   if (items.length !== before) emit();
 }