fix: load mermaid library and fix mermaidOptions provider config

Add mermaid.min.js to angular.json scripts so ngx-markdown can use the
mermaid attribute, and add the required `provide: MERMAID_OPTIONS` key
to satisfy the TypedValueProvider type constraint.

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

Author: lyubov-voloshko

frontend/angular.json

@@ -47,7 +47,7 @@
 						"stylePreprocessorOptions": {
 							"includePaths": ["node_modules/@brumeilde/ngx-theme/presets/material"]
 						},
-						"scripts": [],
+						"scripts": ["node_modules/mermaid/dist/mermaid.min.js"],
 						"extractLicenses": false,
 						"sourceMap": true,
 						"optimization": false,

frontend/src/main.ts

@@ -15,7 +15,7 @@ import { DynamicModule } from 'ng-dynamic-component';
 import { SignalComponentIoModule } from 'ng-dynamic-component/signal-component-io';
 import { provideCharts, withDefaultRegisterables } from 'ng2-charts';
 import { CookieService } from 'ngx-cookie-service';
-import { MarkdownModule, provideMarkdown } from 'ngx-markdown';
+import { MERMAID_OPTIONS, MarkdownModule, provideMarkdown } from 'ngx-markdown';
 import { NgxStripeModule } from 'ngx-stripe';
 import { AppComponent } from './app/app.component';
 import { AppRoutingModule } from './app/app-routing.module';
@@ -127,6 +127,7 @@ bootstrapApplication(AppComponent, {
 		CookieService,
 		provideMarkdown({
 			mermaidOptions: {
+				provide: MERMAID_OPTIONS,
 				useValue: {
 					startOnLoad: false,
 					theme: window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'default',