feat: back to start button

src/components/SVGContent.svelte

@@ -51,6 +51,7 @@
     x: 0,
     y: 0,
   };
+  let panToStart: undefined | (() => void);
 
   onMount(async () => {
     console.info("[SVG] Initializing.");
@@ -219,6 +220,9 @@
       console.debug(`[SVGCONTENT] Panning to start anchor.`);
       panToElement(start, false);
     }
+    if (start) {
+      panToStart = () => panToElement(start, true);
+    }
 
     // Anchors
     console.debug("[SVG] Processing anchors.");
@@ -625,6 +629,9 @@
   {#each audioAreas as audio (audio.id)}
     <AudioArea definition={audio} {bbox} />
   {/each}
+  {#if panToStart !== undefined}
+    <button on:click={() => panToStart()}>zpět na začátek</button>
+  {/if}
   <div class="dev devpanel">
     <div>
       <span>Current viewport position:</span>
@@ -685,6 +692,19 @@
     transition: width 0.2s;
   }
 
+  button {
+    position: fixed;
+    bottom: 0;
+    left: 50%;
+    font-size: 1.5rem;
+    transform: translateX(-50%);
+    padding: 1rem 2rem;
+    margin-bottom: 0.5rem;
+    background: #fefefe;
+    border-radius: 1rem;
+    cursor: pointer;
+  }
+
   .dev {
     display: none;
   }