feat: randomize plot order on every page reload (#3816)

Remove deterministic shuffle seed to ensure plots appear in a new
random order on each F5/reload, even when filters remain unchanged.

Changes:
- Remove hashFilters() function (no longer needed)
- Use Math.random() instead of seeded shuffle
- Applies to both filtered and unfiltered views

Fixes random order behavior on homepage

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: MarkusNeusinger

app/src/hooks/useFilterState.ts

@@ -12,44 +12,17 @@ import { API_URL, BATCH_SIZE } from '../constants';
 import { useHomeState } from '../components/Layout';
 
 /**
- * Seeded random number generator (mulberry32).
+ * Fisher-Yates shuffle algorithm.
  */
-function seededRandom(seed: number): () => number {
-  return () => {
-    let t = (seed += 0x6d2b79f5);
-    t = Math.imul(t ^ (t >>> 15), t | 1);
-    t ^= t + Math.imul(t ^ (t >>> 7), t | 61);
-    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
-  };
-}
-
-/**
- * Fisher-Yates shuffle algorithm with optional seed for deterministic results.
- */
-function shuffleArray<T>(array: T[], seed?: number): T[] {
+function shuffleArray<T>(array: T[]): T[] {
   const shuffled = [...array];
-  const random = seed !== undefined ? seededRandom(seed) : Math.random;
   for (let i = shuffled.length - 1; i > 0; i--) {
-    const j = Math.floor(random() * (i + 1));
+    const j = Math.floor(Math.random() * (i + 1));
     [shuffled[i], shuffled[j]] = [shuffled[j], shuffled[i]];
   }
   return shuffled;
 }
 
-/**
- * Generate a hash from filter state for deterministic shuffle.
- */
-function hashFilters(filters: ActiveFilters): number {
-  const str = JSON.stringify(filters);
-  let hash = 0;
-  for (let i = 0; i < str.length; i++) {
-    const char = str.charCodeAt(i);
-    hash = (hash << 5) - hash + char;
-    hash = hash & hash;
-  }
-  return Math.abs(hash);
-}
-
 /**
  * Parse URL params into ActiveFilters.
  * URL format: ?lib=matplotlib&lib=seaborn (AND) or ?lib=matplotlib,seaborn (OR within group)
@@ -349,9 +322,8 @@ export function useFilterState({
         setGlobalCounts(data.globalCounts || data.counts);
         setOrCounts(data.orCounts || []);
 
-        // Shuffle with deterministic seed based on filters
-        const seed = hashFilters(activeFilters);
-        const shuffled = shuffleArray<PlotImage>(data.images || [], seed);
+        // Shuffle images randomly on each load
+        const shuffled = shuffleArray<PlotImage>(data.images || []);
         setAllImages(shuffled);
 
         // Initial display count