Fix layout shift caused by dynamically loaded Bulletins component

[cemreinanc]

Problem

The Bulletins component in front_end/src/app/(main)/components/bulletins.tsx is loaded dynamically without SSR (ssr: false). This causes a layout shift even if there are no bulletins to show because:

1. During SSR/initial render, the component renders nothing
2. When hydration happens on the client, the component renders and adds mt-12 margin
3. This shifts the content below it

The mt-12 margin is currently in the Bulletins component, but it's actually serving as spacing between the header and page content - a layout concern that shouldn't be tied to bulletins.

Consider these approaches:

1. Move spacing to layout or header itself: Add the spacing directly in layout.tsx on the content container or adjust GlobalHeader to decouple it from the dynamically loaded Bulletins component
2. Server-side fetch: Make the bulletins data fetched on the server so the component can be SSR'd with the correct content/dimensions from the start