fix: HIGH priority — scroll debounce, timing-safe auth, a11y, error logging, cleanup dead modals

- Header: throttle scroll handler via requestAnimationFrame (was firing 60+/sec)
- Auth: use crypto.timingSafeEqual for password and token signature comparison
- A11y: add role="dialog", aria-modal, aria-label to all modals (SignupModal, NewsModal, TeamProfile lightbox)
- A11y: add aria-label to close buttons, menu toggle (with aria-expanded), floating CTA
- A11y: add aria-label to MC Instagram buttons
- Error logging: add console.error with route names to all API catch blocks (admin + public)
- Fix open-day-register error leak (was returning raw DB error to client)
- Fix MasterClasses key={index} → key={item.title}
- Delete 3 unused modal components (BookingModal, MasterClassSignupModal, OpenDaySignupModal) — replaced by unified SignupModal

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app/api/admin/group-bookings/route.ts

@@ -21,7 +21,8 @@ export async function PUT(request: NextRequest) {
       return NextResponse.json({ ok: true });
     }
     return NextResponse.json({ error: "Unknown action" }, { status: 400 });
-  } catch {
+  } catch (err) {
+    console.error("[admin/group-bookings] error:", err);
     return NextResponse.json({ error: "Internal error" }, { status: 500 });
   }
 }

src/app/api/admin/mc-registrations/route.ts

@@ -19,7 +19,8 @@ export async function POST(request: NextRequest) {
     }
     const id = addMcRegistration(masterClassTitle.trim(), name.trim(), instagram.trim(), telegram?.trim() || undefined);
     return NextResponse.json({ ok: true, id });
-  } catch {
+  } catch (err) {
+    console.error("[admin/mc-registrations] error:", err);
     return NextResponse.json({ error: "Internal error" }, { status: 500 });
   }
 }
@@ -48,7 +49,8 @@ export async function PUT(request: NextRequest) {
     }
     updateMcRegistration(id, name.trim(), instagram.trim(), telegram?.trim() || undefined);
     return NextResponse.json({ ok: true });
-  } catch {
+  } catch (err) {
+    console.error("[admin/mc-registrations] error:", err);
     return NextResponse.json({ error: "Internal error" }, { status: 500 });
   }
 }

src/app/api/admin/open-day/bookings/route.ts

@@ -28,7 +28,8 @@ export async function PUT(request: NextRequest) {
       return NextResponse.json({ ok: true });
     }
     return NextResponse.json({ error: "Unknown action" }, { status: 400 });
-  } catch {
+  } catch (err) {
+    console.error("[admin/open-day/bookings] error:", err);
     return NextResponse.json({ error: "Internal error" }, { status: 500 });
   }
 }

src/app/api/admin/open-day/classes/route.ts

@@ -39,7 +39,8 @@ export async function PUT(request: NextRequest) {
     const { id, ...data } = body;
     updateOpenDayClass(id, data);
     return NextResponse.json({ ok: true });
-  } catch {
+  } catch (err) {
+    console.error("[admin/open-day/classes] error:", err);
     return NextResponse.json({ error: "Internal error" }, { status: 500 });
   }
 }

src/app/api/admin/open-day/route.ts

@@ -27,7 +27,8 @@ export async function POST(request: NextRequest) {
     }
     const id = createOpenDayEvent(body);
     return NextResponse.json({ ok: true, id });
-  } catch {
+  } catch (err) {
+    console.error("[admin/open-day] error:", err);
     return NextResponse.json({ error: "Internal error" }, { status: 500 });
   }
 }
@@ -39,7 +40,8 @@ export async function PUT(request: NextRequest) {
     const { id, ...data } = body;
     updateOpenDayEvent(id, data);
     return NextResponse.json({ ok: true });
-  } catch {
+  } catch (err) {
+    console.error("[admin/open-day] error:", err);
     return NextResponse.json({ error: "Internal error" }, { status: 500 });
   }
 }

src/app/api/admin/reminders/route.ts

@@ -30,7 +30,8 @@ export async function PUT(request: NextRequest) {
       status as ReminderStatus | null
     );
     return NextResponse.json({ ok: true });
-  } catch {
+  } catch (err) {
+    console.error("[admin/reminders] error:", err);
     return NextResponse.json({ error: "Internal error" }, { status: 500 });
   }
 }

src/app/api/admin/validate-instagram/route.ts

@@ -20,7 +20,8 @@ export async function GET(request: NextRequest) {
     // Instagram returns 200 for existing profiles, 404 for non-existing
     const valid = res.ok;
     return NextResponse.json({ valid });
-  } catch {
+  } catch (err) {
+    console.error("[admin/validate-instagram] error:", err);
     // Network error or timeout — don't block the user
     return NextResponse.json({ valid: true, uncertain: true });
   }

src/app/api/group-booking/route.ts

@@ -27,7 +27,8 @@ export async function POST(request: NextRequest) {
 
     const id = addGroupBooking(cleanName, cleanPhone, cleanGroup, cleanIg, cleanTg);
     return NextResponse.json({ ok: true, id });
-  } catch {
+  } catch (err) {
+    console.error("[group-booking] POST error:", err);
     return NextResponse.json({ error: "Internal error" }, { status: 500 });
   }
 }

src/app/api/master-class-register/route.ts

@@ -38,7 +38,8 @@ export async function POST(request: Request) {
     );
 
     return NextResponse.json({ ok: true, id });
-  } catch {
+  } catch (err) {
+    console.error("[master-class-register] POST error:", err);
     return NextResponse.json({ error: "Internal error" }, { status: 500 });
   }
 }

src/app/api/open-day-register/route.ts

@@ -58,6 +58,7 @@ export async function POST(request: NextRequest) {
     if (msg.includes("UNIQUE")) {
       return NextResponse.json({ error: "Вы уже записаны на это занятие" }, { status: 409 });
     }
-    return NextResponse.json({ error: msg }, { status: 500 });
+    console.error("[open-day-register] POST error:", e);
+    return NextResponse.json({ error: "Internal error" }, { status: 500 });
   }
 }