feat: booking panel upgrade — refactor, notes, search, manual add, polling

Phase 1 — Refactor:
- Split monolith _shared.tsx into types.ts, BookingComponents, InlineNotes,
  GenericBookingsList, AddBookingModal, SearchBar (no more _ prefix)
- All 3 tabs use GenericBookingsList — shared status workflow, filters, archive

Phase 2 — Features:
- DB migration 13: add notes column to all booking tables
- Inline notes with amber highlight, auto-save 800ms debounce
- Confirm modal comment saves to notes field
- Manual add: 2 tabs (Занятие / Мероприятие), filters expired MCs, Open Day support
- Search bar: cross-table search by name/phone
- 10s polling for real-time updates (bookings page + sidebar badge)
- Status change marks booking as seen (fixes unread count on reset)
- Confirm modal stores human-readable group label instead of raw groupId
- Confirmed group bookings appear in Reminders tab

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

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

@@ -1,5 +1,5 @@
 import { NextRequest, NextResponse } from "next/server";
-import { getMcRegistrations, getAllMcRegistrations, addMcRegistration, updateMcRegistration, toggleMcNotification, deleteMcRegistration, setMcRegistrationStatus } from "@/lib/db";
+import { getMcRegistrations, getAllMcRegistrations, addMcRegistration, updateMcRegistration, toggleMcNotification, deleteMcRegistration, setMcRegistrationStatus, updateBookingNotes } from "@/lib/db";
 
 export async function GET(request: NextRequest) {
   const title = request.nextUrl.searchParams.get("title");
@@ -40,6 +40,14 @@ export async function PUT(request: NextRequest) {
       return NextResponse.json({ ok: true });
     }
 
+    // Set notes
+    if (body.action === "set-notes") {
+      const { id, notes } = body;
+      if (!id) return NextResponse.json({ error: "id is required" }, { status: 400 });
+      updateBookingNotes("mc_registrations", id, notes ?? "");
+      return NextResponse.json({ ok: true });
+    }
+
     // Toggle notification status
     if (body.action === "toggle-notify") {
       const { id, field, value } = body;