Add disabled state constraints to progress adjustment buttons in Anime component

- Disable decrement button when progress is at 0 or below to prevent negative values
- Disable increment button when:
  * Media has defined episodes and progress is complete (>= total episodes)
  * Or when progress has reached next airing episode boundary (nextAiringEpisode - 2)
- Improves user experience by preventing invalid progress adjustments
- Maintains data integrity by stopping users from setting impossible progress values

frontend/src/helperComponents/Anime.svelte

@@ -483,6 +483,7 @@
                     completedAtDate = null;
                 }
               }}
+              disabled={currentAniListAnime.data.MediaList.progress <= 0}
               class="bg-gray-700 hover:bg-gray-600 border-gray-600 border rounded-s-lg p-3 h-11 focus:ring-gray-700 focus:ring-2 focus:outline-none"
             >
               <svg
@@ -541,6 +542,16 @@
                   if (startedAtDate === null) startedAtDate = new Date();
                 }
               }}
+              disabled={(currentAniListAnime.data.MediaList.media.episodes >
+                0 &&
+                currentAniListAnime.data.MediaList.progress >=
+                  currentAniListAnime.data.MediaList.media.episodes) ||
+                (currentAniListAnime.data.MediaList.media.nextAiringEpisode
+                  .episode > 0 &&
+                  currentAniListAnime.data.MediaList.progress >
+                    currentAniListAnime.data.MediaList.media.nextAiringEpisode
+                      .episode -
+                      2)}
               class="bg-gray-700 hover:bg-gray-600 border-gray-600 border rounded-e-lg p-3 h-11 focus:ring-gray-700 focus:ring-2 focus:outline-none"
             >
               <svg