refactor: Remove duplicate layout components and fix memory leaks

[Copilot]

Addresses code review feedback from PR #94: duplicate layout components violating DRY, memory leaks from unsubscribed observables, and missing keyboard accessibility handlers.

Changes

• Removed duplicate layout components: HomeLayoutComponent, MovementsLayoutComponent, and AnalyticsLayoutComponent were identical wrappers containing only <router-outlet />. Routes now reference child components directly.

• Fixed memory leaks: Router event subscriptions in BreadcrumbComponent and SideNavComponent now use takeUntilDestroyed() from @angular/core/rxjs-interop for automatic cleanup.

• Added keyboard accessibility: Theme toggle and logout buttons now handle keydown.enter and keydown.space events with preventDefault() to support keyboard navigation without double-triggering.

Before (routes.ts):

{
  path: 'home',
  component: HomeLayoutComponent,  // Unnecessary wrapper
  children: [...]
}

After:

{
  path: 'home',
  children: [...]  // Direct child routes
}

Before (subscriptions):

ngOnInit(): void {
  this.router.events
    .pipe(filter(...))
    .subscribe(...);  // Never unsubscribed
}

After:

constructor() {
  this.router.events
    .pipe(filter(...), takeUntilDestroyed())
    .subscribe(...);
}

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[Copilot]

Pull request overview

This PR addresses technical debt and improves code quality by removing redundant layout components, fixing memory leaks, and enhancing keyboard accessibility. The changes align with Angular best practices for the zoneless, signal-based architecture used in this application.

Key Changes:

• Eliminated three duplicate layout wrapper components (HomeLayoutComponent, MovementsLayoutComponent, AnalyticsLayoutComponent) that only contained <router-outlet />, simplifying the routing structure
• Fixed memory leaks in BreadcrumbComponent and SideNavComponent by applying takeUntilDestroyed() to router event subscriptions
• Added keyboard navigation support (Enter and Space keys) to theme toggle and logout buttons

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
frontend/src/app/layouts/home-layout/home-layout.component.ts	Removed redundant wrapper component containing only <router-outlet />
frontend/src/app/layouts/movements-layout/movements-layout.component.ts	Removed redundant wrapper component containing only <router-outlet />
frontend/src/app/layouts/analytics-layout/analytics-layout.component.ts	Removed redundant wrapper component containing only <router-outlet />
frontend/src/app/app.routes.ts	Removed references to deleted layout components from route configurations
frontend/src/app/components/ui-library/breadcrumb/breadcrumb.component.ts	Added takeUntilDestroyed() to router subscription for automatic cleanup; moved subscription to constructor
frontend/src/app/components/side-nav-component/side-nav-component.ts	Added takeUntilDestroyed() to router subscription; removed unnecessary OnInit implementation; moved subscription to constructor
frontend/src/app/components/side-nav-component/side-nav-component.html	Added keydown.enter and keydown.space handlers with preventDefault() to theme toggle and logout buttons for keyboard accessibility