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/chatDock.ts

@@ -48,7 +48,8 @@ export function initDock(uid: number): void {
   let restored: DockChat[] = [];
   try {
     const raw = localStorage.getItem(storageKey()!);
-    if (raw) restored = (JSON.parse(raw) as Omit<DockChat, "flash">[]).map((c) => ({ ...c, flash: 0 }));
+    if (raw)
+      restored = (JSON.parse(raw) as Omit<DockChat, "flash">[]).map((c) => ({ ...c, flash: 0 }));
   } catch {
     restored = [];
   }
@@ -60,17 +61,20 @@ export function openChat(partner: PartnerLike): void {
   const existing = chats.find((c) => c.partnerId === partner.id);
   if (existing) {
     // Re-opening focuses it: ensure expanded and move to the front.
-    emit([
-      { ...existing, minimized: false },
-      ...chats.filter((c) => c.partnerId !== partner.id),
-    ]);
+    emit([{ ...existing, minimized: false }, ...chats.filter((c) => c.partnerId !== partner.id)]);
     return;
   }
   emit(
     [
-      { partnerId: partner.id, name: partner.name, avatar: partner.avatar_url, minimized: false, flash: 0 },
+      {
+        partnerId: partner.id,
+        name: partner.name,
+        avatar: partner.avatar_url,
+        minimized: false,
+        flash: 0,
+      },
       ...chats,
-    ].slice(0, MAX_OPEN)
+    ].slice(0, MAX_OPEN),
   );
 }
 
@@ -81,9 +85,15 @@ export function notifyIncoming(partner: PartnerLike): void {
   if (!existing) {
     emit(
       [
-        { partnerId: partner.id, name: partner.name, avatar: partner.avatar_url, minimized: false, flash: 1 },
+        {
+          partnerId: partner.id,
+          name: partner.name,
+          avatar: partner.avatar_url,
+          minimized: false,
+          flash: 1,
+        },
         ...chats,
-      ].slice(0, MAX_OPEN)
+      ].slice(0, MAX_OPEN),
     );
     return;
   }
@@ -105,6 +115,6 @@ export function useDockChats(): DockChat[] {
       return () => subs.delete(cb);
     },
     () => chats,
-    () => chats
+    () => chats,
   );
 }