feat: web admin panel + better-sqlite3 migration + Docker fixes

- Added Express.js admin panel on port 3001 (ADMIN_PORT env)
  - Dashboard: stats (users, products, purchases, revenue)
  - Users: list, details, ban/unban toggle
  - Products: CRUD by category
  - Wallets: list with balances
  - Purchases: history with filters
  - Audit log: view audit trail
  - Auth: token-based login with ADMIN_SECRET env var
- Migrated sqlite3 → better-sqlite3
  - database.js: async adapter (runAsync/allAsync/getAsync)
  - purchaseService.js: lastID → lastInsertRowid
  - userService.js: lastID → lastInsertRowid
  - Removed sqlite3 from package.json
- Fixed: dotenv/config import added to index.js
- Fixed: ENCRYPTION_KEY validation (32+ char hex)
- Fixed: Dockerfile multi-stage build (no python needed)
- Fixed: Docker DNS (network: host in build)
- Fixed: docker-compose port 3001, healthcheck on 3001
- Added express, cookie-parser, pino-pretty, better-sqlite3 deps

package.json

@@ -10,6 +10,8 @@
     "archiver": "^7.0.1",
     "axios": "^1.7.7",
     "better-sqlite3": "^11.10.0",
+    "cookie-parser": "^1.4.6",
+    "express": "^4.21.0",
     "bip39": "^3.1.0",
     "bitcoinjs-lib": "^6.1.6",
     "csv-writer": "^1.6.0",
@@ -20,7 +22,7 @@
     "hdkey": "^2.1.0",
     "node-telegram-bot-api": "^0.64.0",
     "pino": "^8.21.0",
-    "sqlite3": "^5.1.6",
+    "pino-pretty": "^13.1.3",
     "tiny-secp256k1": "^2.2.3"
   },
   "devDependencies": {