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/classes/page.tsx

@@ -0,0 +1,94 @@
+"use client";
+
+import { SectionEditor } from "../_components/SectionEditor";
+import { InputField, TextareaField } from "../_components/FormField";
+import { ArrayEditor } from "../_components/ArrayEditor";
+
+const ICON_OPTIONS = [
+  "sparkles", "flame", "wind", "zap", "star", "monitor",
+  "heart", "music", "dumbbell", "trophy",
+];
+
+interface ClassesData {
+  title: string;
+  items: {
+    name: string;
+    description: string;
+    icon: string;
+    detailedDescription?: string;
+    images?: string[];
+  }[];
+}
+
+export default function ClassesEditorPage() {
+  return (
+    <SectionEditor<ClassesData> sectionKey="classes" title="Направления">
+      {(data, update) => (
+        <>
+          <InputField
+            label="Заголовок секции"
+            value={data.title}
+            onChange={(v) => update({ ...data, title: v })}
+          />
+
+          <ArrayEditor
+            label="Направления"
+            items={data.items}
+            onChange={(items) => update({ ...data, items })}
+            renderItem={(item, _i, updateItem) => (
+              <div className="space-y-3">
+                <div className="grid gap-3 sm:grid-cols-2">
+                  <InputField
+                    label="Название"
+                    value={item.name}
+                    onChange={(v) => updateItem({ ...item, name: v })}
+                  />
+                  <div>
+                    <label className="block text-sm text-neutral-400 mb-1.5">
+                      Иконка
+                    </label>
+                    <select
+                      value={item.icon}
+                      onChange={(e) =>
+                        updateItem({ ...item, icon: e.target.value })
+                      }
+                      className="w-full rounded-lg border border-white/10 bg-neutral-800 px-4 py-2.5 text-white outline-none focus:border-gold transition-colors"
+                    >
+                      {ICON_OPTIONS.map((icon) => (
+                        <option key={icon} value={icon}>
+                          {icon}
+                        </option>
+                      ))}
+                    </select>
+                  </div>
+                </div>
+                <TextareaField
+                  label="Краткое описание"
+                  value={item.description}
+                  onChange={(v) => updateItem({ ...item, description: v })}
+                  rows={2}
+                />
+                <TextareaField
+                  label="Подробное описание"
+                  value={item.detailedDescription || ""}
+                  onChange={(v) =>
+                    updateItem({ ...item, detailedDescription: v })
+                  }
+                  rows={4}
+                />
+              </div>
+            )}
+            createItem={() => ({
+              name: "",
+              description: "",
+              icon: "sparkles",
+              detailedDescription: "",
+              images: [],
+            })}
+            addLabel="Добавить направление"
+          />
+        </>
+      )}
+    </SectionEditor>
+  );
+}