feat: redondeo en el pie de los documentos de ventas y compras (visible según OADM.RoundMthd) y endpoint /api/company/settings

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

apps/web/src/app/features/documents/document-form.page.html

@@ -214,6 +214,25 @@
         }
       </div>
     }
+    @case ('rounding') {
+      @if (roundingEnabled()) {
+        <sbo-field [label]="f.label">
+          <sbo-checkbox
+            ariaLabel="Redondear el total del documento"
+            [readonly]="readOnly() || locked(f)"
+            [value]="header()['Rounding'] === 'tYES'"
+            (valueChange)="setHeader('Rounding', $event ? 'tYES' : 'tNO')"
+          />
+          <sbo-number
+            ariaLabel="Importe del redondeo"
+            [decimals]="2"
+            [readonly]="readOnly() || locked(f) || header()['Rounding'] !== 'tYES'"
+            [value]="+str(header()['RoundingDiffAmount'])"
+            (valueChange)="setHeader('RoundingDiffAmount', $event ?? 0)"
+          />
+        </sbo-field>
+      }
+    }
     @case ('computed') {
       <sbo-text-field [label]="f.label" readonly [value]="computedValue(f.source)" />
     }