feat: добавить генерацию image variants

- добавлен shared config presets, custom transforms и allowlist hosts
- реализованы Backend endpoints для assets, presets и variants
- добавлена orchestration через PostgreSQL, RabbitMQ, S3 и worker
- обновлён Gateway read-through flow с L1 cache и корректным Vary: Accept
- добавлена миграция resize_mode для variants lookup
- обновлены dev scripts, env template, lockfile и документация

packages/image-config/package.json

@@ -0,0 +1,22 @@
+{
+  "name": "@image-platform/image-config",
+  "version": "0.1.0",
+  "private": true,
+  "exports": {
+    ".": {
+      "types": "./src/index.ts",
+      "require": "./dist/index.js",
+      "import": "./dist/index.js",
+      "default": "./dist/index.js"
+    }
+  },
+  "types": "./src/index.ts",
+  "scripts": {
+    "build": "tsc -p tsconfig.build.json",
+    "typecheck": "tsc --noEmit -p tsconfig.json"
+  },
+  "devDependencies": {
+    "@types/node": "^25.6.0",
+    "typescript": "^6.0.3"
+  }
+}