refactor(bot): remove old Express/EJS admin panel, add standalone health server (v1.2.7)

- Delete src/admin/ (1012 files: routes, views, public, auth) — old admin replaced by Next.js admin-next/
- Add src/healthServer.js: minimal HTTP /health on port 3001 for Docker healthcheck
- src/index.js uses startHealthServer instead of startAdminPanel
- Remove admin-dependent test (adminDeleteFeedback.test.js); 30 tests pass
- Remove ejs/express-ejs-layouts/express/cookie-parser/multer from deps
- admin-next: prisma binaryTargets for linux-arm64-openssl (arm64 prod)
- VERSION.md v1.2.7
- Bot adminHandlers (Telegram commands) kept — data preserved in shared SQLite

VERSION.md

@@ -4,15 +4,17 @@
 
 1. Edit this file (`VERSION.md`)
 2. Add new entry under `## Changelog`
-3. Bump version in `src/admin/views/partials/app-sidebar.ejs`
-4. Commit all changes together
+3. Commit all changes together
 
 ## Current Version
 
-**v1.2.6** — 2026-08-05
+**v1.2.7** — 2026-08-08
 
 ## Changelog
 
+### v1.2.7 — 2026-08-08
+- **refactor**: Remove old Express/EJS admin panel (replaced by Next.js admin in admin-next/); bot now has standalone health server; SUPER_ADMIN_SECRET for admin auth
+
 ### v1.2.6 — 2026-08-05
 - **fix**: dead admin callback buttons — `prod_district_` (Back to Categories after adding category, pipe-delimited format) and `admin_users` (Back to User List) now registered
 - **fix**: no-op placeholder buttons (`current_page`, `current_quantity`, `no_action`) no longer log "No handler" warns