feat(web): el almacén y el impuesto elegidos en la primera línea se copian a las de abajo

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

apps/web/src/app/shared/grid/lines-grid.ts

@@ -141,7 +141,15 @@ export class LinesGrid {
 
   private replace(row: number, line: GridLine, key: string): void {
     const next = this.recalc()?.(line, key) ?? line;
-    this.lines.update((ls) => ls.map((l, i) => (i === row ? next : l)));
+    const spread = row === 0 && this.columns().some((c) => c.key === key && c.propagate) && next[key] !== this.lines()[0]?.[key];
+    this.lines.update((ls) =>
+      ls.map((l, i) => {
+        if (i === row) return next;
+        if (!spread || i === 0) return l;
+        const copy = { ...l, [key]: next[key] };
+        return this.recalc()?.(copy, key) ?? copy;
+      }),
+    );
   }
 
   // --- filas -----------------------------------------------------------------------------