feat: admin panel with SQLite, auth, and calendar-style schedule editor

Complete admin panel for content management:
- SQLite database with better-sqlite3, seed script from content.ts
- Simple password auth with HMAC-signed cookies (Edge + Node compatible)
- 9 section editors: meta, hero, about, team, classes, schedule, pricing, FAQ, contact
- Team CRUD with image upload and drag reorder
- Schedule editor with Google Calendar-style visual timeline (colored blocks, overlap detection, click-to-add)
- All public components refactored to accept data props from DB (with fallback to static content)
- Middleware protecting /admin/* and /api/admin/* routes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/admin/_components/ArrayEditor.tsx

@@ -0,0 +1,94 @@
+"use client";
+
+import { Plus, Trash2, ChevronUp, ChevronDown } from "lucide-react";
+
+interface ArrayEditorProps<T> {
+  items: T[];
+  onChange: (items: T[]) => void;
+  renderItem: (item: T, index: number, update: (item: T) => void) => React.ReactNode;
+  createItem: () => T;
+  label?: string;
+  addLabel?: string;
+}
+
+export function ArrayEditor<T>({
+  items,
+  onChange,
+  renderItem,
+  createItem,
+  label,
+  addLabel = "Добавить",
+}: ArrayEditorProps<T>) {
+  function updateItem(index: number, item: T) {
+    const updated = [...items];
+    updated[index] = item;
+    onChange(updated);
+  }
+
+  function removeItem(index: number) {
+    onChange(items.filter((_, i) => i !== index));
+  }
+
+  function moveItem(index: number, direction: -1 | 1) {
+    const newIndex = index + direction;
+    if (newIndex < 0 || newIndex >= items.length) return;
+    const updated = [...items];
+    [updated[index], updated[newIndex]] = [updated[newIndex], updated[index]];
+    onChange(updated);
+  }
+
+  return (
+    <div>
+      {label && (
+        <h3 className="text-sm font-medium text-neutral-300 mb-3">{label}</h3>
+      )}
+
+      <div className="space-y-3">
+        {items.map((item, i) => (
+          <div
+            key={i}
+            className="rounded-lg border border-white/10 bg-neutral-900/50 p-4"
+          >
+            <div className="flex items-start justify-between gap-2 mb-3">
+              <div className="flex gap-1">
+                <button
+                  type="button"
+                  onClick={() => moveItem(i, -1)}
+                  disabled={i === 0}
+                  className="rounded p-1 text-neutral-500 hover:text-white disabled:opacity-30 transition-colors"
+                >
+                  <ChevronUp size={16} />
+                </button>
+                <button
+                  type="button"
+                  onClick={() => moveItem(i, 1)}
+                  disabled={i === items.length - 1}
+                  className="rounded p-1 text-neutral-500 hover:text-white disabled:opacity-30 transition-colors"
+                >
+                  <ChevronDown size={16} />
+                </button>
+              </div>
+              <button
+                type="button"
+                onClick={() => removeItem(i)}
+                className="rounded p-1 text-neutral-500 hover:text-red-400 transition-colors"
+              >
+                <Trash2 size={16} />
+              </button>
+            </div>
+            {renderItem(item, i, (updated) => updateItem(i, updated))}
+          </div>
+        ))}
+      </div>
+
+      <button
+        type="button"
+        onClick={() => onChange([...items, createItem()])}
+        className="mt-3 flex items-center gap-2 rounded-lg border border-dashed border-white/20 px-4 py-2.5 text-sm text-neutral-400 hover:text-white hover:border-white/40 transition-colors"
+      >
+        <Plus size={16} />
+        {addLabel}
+      </button>
+    </div>
+  );
+}