refactor(theme): remove obsolete compatibility

src/app/services/theme-service.spec.ts

@@ -1,42 +0,0 @@
-import { TestBed } from '@angular/core/testing';
-import { provideZonelessChangeDetection } from '@angular/core';
-import { ThemeService } from './theme-service';
-
-describe('ThemeService', () => {
-	let service: ThemeService;
-
-	beforeEach(() => {
-		TestBed.configureTestingModule({
-			providers: [provideZonelessChangeDetection()],
-		});
-		service = TestBed.inject(ThemeService);
-	});
-
-	it('should be created', () => {
-		expect(service).toBeTruthy();
-	});
-
-	it('should initialize with system preference', () => {
-		expect(service.isLightMode()).toBeDefined();
-	});
-
-	it('should toggle theme', () => {
-		const initialMode = service.isLightMode();
-		service.toggleTheme();
-		expect(service.isLightMode()).toBe(!initialMode);
-	});
-
-	it('should force light mode when specified', () => {
-		service.toggleTheme(true);
-		expect(service.isLightMode()).toBe(true);
-		expect(document.body.classList.contains('light-mode')).toBe(true);
-		expect(document.body.classList.contains('dark-mode')).toBe(false);
-	});
-
-	it('should force dark mode when specified', () => {
-		service.toggleTheme(false);
-		expect(service.isLightMode()).toBe(false);
-		expect(document.body.classList.contains('light-mode')).toBe(false);
-		expect(document.body.classList.contains('dark-mode')).toBe(true);
-	});
-});

src/app/services/theme-service.ts

@@ -13,7 +13,6 @@ export class ThemeService {
 		const preference = this.selectedPreference();
 		return preference === 'system' ? (this.systemIsLight() ? 'light' : 'dark') : preference;
 	});
-	readonly isLightMode = computed(() => this.effectiveTheme() === 'light');
 	readonly nextThemePreference = computed(() => this.nextPreference(this.selectedPreference()));
 
 	constructor() {
@@ -26,18 +25,13 @@ export class ThemeService {
 		});
 	}
 
-	setThemePreference(preference: ThemePreference): void {
-		this.selectedPreference.set(preference);
-		this.applyEffectiveTheme();
+	toggleTheme(): void {
+		this.setThemePreference(this.nextThemePreference());
 	}
 
-	toggleTheme(forceLight?: boolean): void {
-		if (forceLight !== undefined) {
-			this.setThemePreference(forceLight ? 'light' : 'dark');
-			return;
-		}
-
-		this.setThemePreference(this.nextThemePreference());
+	private setThemePreference(preference: ThemePreference): void {
+		this.selectedPreference.set(preference);
+		this.applyEffectiveTheme();
 	}
 
 	private nextPreference(preference: ThemePreference): ThemePreference {