feat: finish demo — Angular 22 + Material UI, role management, schema and Docker cleanup

Frontend
- Upgrade Angular 19 -> 22 (TypeScript 6, new control flow), drop unused
  packages (bootstrap, jquery, popper, ng-bootstrap, webpack)
- Move the UI to Angular Material: toolbar with user menu, tutorials list,
  add/edit forms, admin users table with role editing dialog, profile,
  home page with published tutorials, registration form, login dialog
- Guard routes: login required for add/edit/profile, admin role for /admin
- Remove the /login, Moderator and User pages, event bus, auth interceptor
  and other dead code

Backend
- Add PUT /api/users/{id}/roles (admin only) that keeps at least one admin
  and does not let an admin drop their own admin role
- Tighten security: read tutorials publicly, change them only when logged
  in, users/roles API for admins only; hide password hashes in JSON
- Remove unused Settings and Test endpoints, DTO mappers, commented code
- Flyway V2 aligns the schema with the entities (bigint ids, tutorials PK,
  identity ids); Hibernate now runs with ddl-auto: validate

Docker
- Three-stage Dockerfile (Node build, Gradle build, JRE runtime) with
  layer caching, non-root user and healthcheck; add .dockerignore
- docker-compose waits for a healthy Postgres, always rebuilds the image,
  no longer mounts the Docker socket

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docker-compose.yml

@@ -1,13 +1,11 @@
 services:
   demo-monolith-postgres:
     image: postgres:16-alpine
-    restart: always
+    restart: unless-stopped
     environment:
       POSTGRES_DB: jambotron_monolith
       POSTGRES_USER: jambotron_admin
       POSTGRES_PASSWORD: jambo_secret_pass
-    expose:
-      - "5432"
     healthcheck:
       test: ["CMD-SHELL", "pg_isready -U jambotron_admin -d jambotron_monolith"]
       interval: 3s
@@ -20,19 +18,23 @@ services:
 
   app:
     build: .
-    restart: always
+    # Собирать образ при каждом `docker compose up`, иначе compose молча запускает старый образ
+    pull_policy: build
+    restart: unless-stopped
+    # Ждём, пока база начнёт принимать подключения, иначе Flyway падает на старте
+    depends_on:
+      demo-monolith-postgres:
+        condition: service_healthy
     ports:
       - "8080:8080"
     environment:
-      - SPRING_DATASOURCE_URL=jdbc:postgresql://demo-monolith-postgres:5432/jambotron_monolith
-      - SPRING_DATASOURCE_USERNAME=jambotron_admin
-      - SPRING_DATASOURCE_PASSWORD=jambo_secret_pass
-      - SPRING_DATASOURCE_DRIVER-CLASS-NAME=org.postgresql.Driver
-      - SPRING_FLYWAY_URL=jdbc:postgresql://demo-monolith-postgres:5432/jambotron_monolith?options=-c%20timezone=UTC
-      - SPRING_FLYWAY_USER=jambotron_admin
-      - SPRING_FLYWAY_PASSWORD=jambo_secret_pass
-    volumes:
-      - /var/run/docker.sock:/var/run/docker.sock
+      SPRING_DATASOURCE_URL: jdbc:postgresql://demo-monolith-postgres:5432/jambotron_monolith
+      SPRING_DATASOURCE_USERNAME: jambotron_admin
+      SPRING_DATASOURCE_PASSWORD: jambo_secret_pass
+      # В application.yaml Flyway настроен на localhost отдельно от datasource — переопределяем
+      SPRING_FLYWAY_URL: jdbc:postgresql://demo-monolith-postgres:5432/jambotron_monolith?options=-c%20timezone=UTC
+      SPRING_FLYWAY_USER: jambotron_admin
+      SPRING_FLYWAY_PASSWORD: jambo_secret_pass
     networks:
       - demo-monolith
 
@@ -40,4 +42,4 @@ volumes:
   postgres_data:
 
 networks:
-  demo-monolith:
+  demo-monolith: