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/modules.ts

@@ -48,11 +48,35 @@ const MODULES: readonly ModuleDef[] = [
   { id: "playlists", labelKey: "header.account.playlists", icon: ListVideo },
   { id: "plex", labelKey: "plex.navLabel", icon: Clapperboard, gate: (me) => me.plex_enabled },
   { id: "notifications", labelKey: "inbox.navLabel", icon: Bell, hasBadge: true },
-  { id: "messages", labelKey: "messages.navLabel", icon: MessageSquare, hasBadge: true, gate: notDemo },
-  { id: "downloads", labelKey: "downloads.navLabel", icon: Download, hasBadge: true, gate: notDemo },
+  {
+    id: "messages",
+    labelKey: "messages.navLabel",
+    icon: MessageSquare,
+    hasBadge: true,
+    gate: notDemo,
+  },
+  {
+    id: "downloads",
+    labelKey: "downloads.navLabel",
+    icon: Download,
+    hasBadge: true,
+    gate: notDemo,
+  },
   { id: "stats", labelKey: "header.account.stats", icon: BarChart3 },
-  { id: "scheduler", labelKey: "header.account.scheduler", icon: Activity, system: true, gate: isAdmin },
-  { id: "config", labelKey: "header.account.config", icon: SlidersHorizontal, system: true, gate: isAdmin },
+  {
+    id: "scheduler",
+    labelKey: "header.account.scheduler",
+    icon: Activity,
+    system: true,
+    gate: isAdmin,
+  },
+  {
+    id: "config",
+    labelKey: "header.account.config",
+    icon: SlidersHorizontal,
+    system: true,
+    gate: isAdmin,
+  },
   { id: "users", labelKey: "header.account.users", icon: Users, system: true, gate: isAdmin },
   { id: "audit", labelKey: "header.account.audit", icon: ScrollText, system: true, gate: isAdmin },
 ];
@@ -69,9 +93,10 @@ const SETTINGS_MODULE: ModuleDef = {
 // place. If a Page is left unregistered, moduleDef()/moduleLabelKey[] return undefined and NavSidebar
 // throws on `.icon`; the coverage isn't compiler-enforced here because the ordered array can't also
 // be an exhaustive Page map, so treat the array as the checklist when the Page union grows.
-const BY_ID = Object.fromEntries(
-  [...MODULES, SETTINGS_MODULE].map((m) => [m.id, m]),
-) as Record<Page, ModuleDef>;
+const BY_ID = Object.fromEntries([...MODULES, SETTINGS_MODULE].map((m) => [m.id, m])) as Record<
+  Page,
+  ModuleDef
+>;
 
 // Look up a module's definition by page id (every Page is covered, incl. settings).
 export function moduleDef(id: Page): ModuleDef {