fix(frontend): submit-time data flow (rating scale, table reactivity)

- rating submitted doubled: the * 2 belonged to the retired 0-5
  slider scale while StarInput already works in backend 0-10 units,
  so every rating arrived doubled (9 became 18, both backends
  rejected it); form value now passes through unscaled, display and
  words map already native 0-10
- StarInput gains an optional name prop rendering a hidden input,
  restoring the rating form field the old slider exposed; Rating
  passes name="rating"
- table updates go immutable (new array every path): in-place
  mutation with the same reference never reliably invalidated the
  Svelte 5 $derived, which left the grid stale after successful
  submits; replace-or-append semantics unchanged
- per-page dropdown reads the event value synchronously (Svelte 5
  nulls currentTarget after dispatch, crashing the old
  read-inside-.then)
- detail poster column shares a flex centering context so poster and
  stars align by construction at every width

frontend/src/helperComponents/Anime.svelte

@@ -169,7 +169,9 @@
     for (let field of formData) {
       const [key, value] = field;
       if (key === "rating") {
-        submitData.rating = Number(value) * 2;
+        // Form value is already 0-10 (StarInput works in backend units).
+        // The old * 2 belonged to the retired 0-5 slider scale.
+        submitData.rating = Number(value);
         continue;
       }
       if (key === "episodes") {

frontend/src/helperComponents/Pagination.svelte

@@ -43,14 +43,14 @@
   function changeCountPerPage(
     e: Event & { currentTarget: HTMLSelectElement },
   ): void {
-    App.GetAniListUserWatchingList(1, Number(e.currentTarget.value), sort).then(
-      (result) => {
-        animePerPage.set(Number(e.currentTarget.value));
+    // Read synchronously: Svelte 5 nulls currentTarget after dispatch.
+    const count = Number(e.currentTarget.value);
+    App.GetAniListUserWatchingList(1, count, sort).then((result) => {
+      animePerPage.set(count);
       watchListPage.set(1);
       aniListWatchlist.set(result);
       aniListLoggedIn.set(true);
-      },
-    );
+    });
   }
 </script>
 

frontend/src/helperComponents/Rating.svelte

@@ -19,7 +19,7 @@
 </script>
 
 <div>
-    <StarInput bind:value={score} min={0} max={10} step={1} />
+    <StarInput bind:value={score} min={0} max={10} step={1} name="rating" />
     <p>Rating:  {score}</p>
     <p>{ratingInWords[score]}</p>
 </div>

frontend/src/helperModules/AddAnimeServiceToTable.svelte

@@ -3,19 +3,19 @@
     import { tableItems } from "./GlobalVariablesAndHelperFunctions.svelte"
 
     export function AddAnimeServiceToTable(animeItem: TableItem) {
+        // Always return a NEW array: in-place mutation with the same
+        // reference does not reliably invalidate $derived consumers
+        // under Svelte 5, which left the table stale after submits.
         tableItems.update((table) => {
-            if (table.length === 0) {
-                table.push(animeItem)
-            } else {
-                for (const [index, tableItem] of table.entries()) {
-                    if(tableItem.service === animeItem.service) {
-                        table[index] = animeItem
-                        return table
+            const index = table.findIndex(
+                (tableItem) => tableItem.service === animeItem.service,
+            );
+            if (index === -1) {
+                return [...table, animeItem];
             }
-                }
-                table.push(animeItem)
-            }
-            return table
+            return table.map((tableItem, i) =>
+                i === index ? animeItem : tableItem,
+            );
         })
     }
 </script>

frontend/src/star-rating/StarInput.svelte

@@ -21,6 +21,7 @@
         step = 0.5,
         count = 5,
         disabled = false,
+        name,
         starConfig = {
             size: 32,
             fillColor: '#F9ED4F',
@@ -36,6 +37,10 @@
         step?: number;
         count?: number;
         disabled?: boolean;
+        // When set, renders a hidden input so the value submits with a
+        // surrounding <form> via FormData (the old slider exposed
+        // name="rating" the same way).
+        name?: string;
         starConfig?: StarColors;
         onchange?: (value: number) => void;
     } = $props();
@@ -99,6 +104,9 @@
     onmouseleave={onHoverLeave}
 >
     <div class="stars">
+        {#if name !== undefined}
+            <input type="hidden" name={name} value={value} />
+        {/if}
         {#each Array(count) as _, i}
             <button
                 type="button"