fix(layout): make stacked notes stick horizontally when scrolling

Add left offset to each stacked note so position: sticky activates
during horizontal scroll, pinning notes progressively to the right
of the readme column at calc((index + 1) * var(--note-width)).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/FluxNote.vue

@@ -124,6 +124,7 @@ onUnmounted(() => {
       :user="user"
       :repo="repo"
       :title="titles[stackedNote]"
+      :style="{ left: `calc(${index + 1} * var(--note-width))` }"
     />
   </main>
 </template>