Add EvoSync v3 environment scaffold

FastAPI + Celery + Redis + MariaDB stack with 6-service docker-compose.
Includes project skeleton (config, database, models, tasks, migrations)
and health endpoint with passing test.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.env.example

@@ -1,11 +1,17 @@
-DATABASE_URL=mysql+pymysql://evosync:evosync@db:3306/evosync
-SECRET_KEY=your-random-secret-key-here
-BASE_URL=http://localhost:8000
-
-EVOTOR_APP_ID=your-evotor-app-id
-EVOTOR_WEBHOOK_SECRET=your-webhook-secret
-
-DB_ROOT_PASSWORD=rootpass
+# Database
+DB_ROOT_PASSWORD=rootpassword
 DB_NAME=evosync
 DB_USER=evosync
 DB_PASSWORD=evosync
+
+# App
+SECRET_KEY=change-me-in-production
+BASE_URL=https://evosync.ru
+
+# Evotor
+EVOTOR_APP_ID=
+EVOTOR_WEBHOOK_SECRET=
+
+# Celery Flower
+FLOWER_USER=admin
+FLOWER_PASSWORD=changeme