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/components/sections/About.tsx

@@ -1,16 +1,25 @@
 import { Users, Layers, MapPin } from "lucide-react";
-import { siteContent } from "@/data/content";
 import { SectionHeading } from "@/components/ui/SectionHeading";
 import { Reveal } from "@/components/ui/Reveal";
+import type { SiteContent } from "@/types/content";
 
-const stats = [
-  { icon: <Users size={22} />, value: "16", label: "тренеров" },
-  { icon: <Layers size={22} />, value: "6", label: "направлений" },
-  { icon: <MapPin size={22} />, value: "2", label: "зала в Минске" },
-];
+interface AboutStats {
+  trainers: number;
+  classes: number;
+  locations: number;
+}
 
-export function About() {
-  const { about } = siteContent;
+interface AboutProps {
+  data: SiteContent["about"];
+  stats: AboutStats;
+}
+
+export function About({ data: about, stats }: AboutProps) {
+  const statItems = [
+    { icon: <Users size={22} />, value: String(stats.trainers), label: "тренеров" },
+    { icon: <Layers size={22} />, value: String(stats.classes), label: "направлений" },
+    { icon: <MapPin size={22} />, value: String(stats.locations), label: "зала в Минске" },
+  ];
 
   return (
     <section id="about" className="section-glow relative section-padding bg-neutral-100 dark:bg-[#080808]">
@@ -33,7 +42,7 @@ export function About() {
         {/* Stats */}
         <Reveal>
           <div className="mx-auto mt-14 grid max-w-3xl grid-cols-3 gap-4 sm:gap-8">
-            {stats.map((stat, i) => (
+            {statItems.map((stat, i) => (
               <div
                 key={i}
                 className="group flex flex-col items-center gap-3 rounded-2xl border border-neutral-200 bg-white/50 p-6 transition-all duration-300 hover:border-gold/30 sm:p-8 dark:border-white/[0.06] dark:bg-white/[0.02] dark:hover:border-gold/20"