refactor: move scaler out of $lib/server so it can run in browser

RecipeView needs scaleIngredients on the client for live portion scaling.
Moved scaler.ts from $lib/server/recipes/ to $lib/recipes/.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/components/RecipeView.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { scaleIngredients } from '$lib/server/recipes/scaler';
+  import { scaleIngredients } from '$lib/recipes/scaler';
   import type { Recipe } from '$lib/types';
 
   type Props = {