feat: Add Banner component across Gallery, Openings, and Homepage layouts

- Integrated `Banner.astro` into `Gallery.astro`, `Openings.astro`, and `index.astro` for consistent banner display.

src/pages/Gallery.astro

@@ -1,9 +1,11 @@
 ---
 import Layout from "../components/Layout.astro";
+import Banner from "../components/Banner.astro";
 ---
 
 <Layout>
-	
+	<Banner />
+
 	<h1>Gallery</h1>
 
 	<p>Hier findest du alle aktuellen und kommenden Gallery im Gallus Pub.</p>

src/pages/Openings.astro

@@ -1,8 +1,10 @@
 ---
 import Layout from "../components/Layout.astro";
+import Banner from "../components/Banner.astro";
 ---
 
 <Layout>
+	<Banner />
 
 	<h1>Openings</h1>
 

src/pages/index.astro

@@ -1,5 +1,6 @@
 ---
 import Layout from "../components/Layout.astro";
+import Banner from "../components/Banner.astro";
 import Hero from "../components/Hero.astro";
 import Welcome from "../components/Welcome.astro";
 import EventsGrid from "../components/EventsGrid.astro";
@@ -87,6 +88,7 @@ const images = [
 
 <Layout>
 	<Hero id="hero" />
+	<Banner />
 	<Welcome id="welcome" />
 	<EventsGrid id="events" events={events} />
 	<ImageCarousel id="gallery" images={images} />