feat (frontend): add payment method.

tienda_ilusion/don_confiao/frontend/don-confiao/src/components/Purchase.vue

@@ -116,6 +116,13 @@
           readonly
           persistent-placeholder="true"
         ></v-text-field>
+        <v-select
+          :items="payment_methods"
+          v-model="purchase.payment_method"
+          item-title="text"
+          item-value="value"
+          label="Pago en"
+        ></v-select>
         <v-btn @click="submit" color="green">Comprar</v-btn>
       </v-form>
     </v-container>
@@ -137,10 +144,16 @@
        valid: false,
        client_search: '',
        product_search: '',
+       payment_methods: [
+         {'text': 'Efectivo', 'value': 'CASH'},
+         {'text': 'Confiar', 'value': 'CONFIAR'},
+         {'text': 'Bancolombia', 'value': 'BANCOLOMBIA'},
+       ],
        purchase: {
          date: this.getCurrentDate(),
          customer: null,
          notes: '',
+         payment_method: {'text': 'Efectivo', 'value': 'CASH'},
          saleline_set: [{product:'', unit_price: 0, quantity: 0, unit: ''}],
        },
        rules: {