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>

spring-angular-ui/package.json

@@ -3,7 +3,7 @@
   "version": "0.0.0",
   "scripts": {
     "ng": "ng",
-    "start": "ng serve",
+    "start": "ng serve --proxy-config src/proxy.conf.json",
     "build": "ng build",
     "build_dev": "ng build --configuration development",
     "watch": "ng build --watch --configuration development",
@@ -11,38 +11,33 @@
   },
   "private": true,
   "dependencies": {
-    "@angular/animations": "^19.2.11",
-    "@angular/cdk": "^19.2.16",
-    "@angular/common": "^19.2.11",
-    "@angular/compiler": "^19.2.11",
-    "@angular/core": "^19.2.11",
-    "@angular/forms": "^19.2.11",
-    "@angular/material": "^19.2.16",
-    "@angular/platform-browser": "^19.2.11",
-    "@angular/platform-browser-dynamic": "^19.2.11",
-    "@angular/router": "^19.2.11",
-    "@ng-bootstrap/ng-bootstrap": "^17.0.0",
-    "@popperjs/core": "^2.11.8",
-    "bootstrap": "^5.3.3",
-    "jquery": "^3.7.1",
-    "popper.js": "^1.16.1",
+    "@angular/animations": "^22.2.3",
+    "@angular/cdk": "^22.2.3",
+    "@angular/common": "^22.2.3",
+    "@angular/compiler": "^22.2.3",
+    "@angular/core": "^22.2.3",
+    "@angular/forms": "^22.2.3",
+    "@angular/material": "^22.2.3",
+    "@angular/platform-browser": "^22.2.3",
+    "@angular/platform-browser-dynamic": "^22.2.3",
+    "@angular/router": "^22.2.3",
     "rxjs": "~7.8.0",
     "tslib": "^2.3.0",
     "zone.js": "~0.15.0"
   },
   "devDependencies": {
-    "@angular-devkit/build-angular": "^19.2.12",
-    "@angular/cli": "^19.2.12",
-    "@angular/compiler-cli": "~19.2.11",
+    "@angular-devkit/build-angular": "^22.2.3",
+    "@angular/cli": "^22.2.3",
+    "@angular/compiler-cli": "~22.2.3",
     "@types/jasmine": "~3.6.0",
     "@types/node": "^12.11.1",
+    "istanbul-lib-instrument": "^6.0.3",
     "jasmine-core": "~3.7.0",
     "karma": "~6.3.0",
     "karma-chrome-launcher": "~3.1.0",
     "karma-coverage": "~2.0.3",
     "karma-jasmine": "~4.0.0",
     "karma-jasmine-html-reporter": "^1.5.0",
-    "typescript": "~5.8.3",
-    "webpack": "^5.93.0"
+    "typescript": "~6.0.3"
   }
 }