[ADD] pos_payment_method_cashdro_rounding: migration to 18.0

Migrated from the 17.0 branch (4fbf328). APIs that no longer exist in 18.0:

* `order.selected_paymentline` -> `order.get_selected_paymentline()`
* `ErrorPopup` + `env.services.popup` -> `AlertDialog` + `env.services.dialog`
* `/** @odoo-module */`, implicit in `.esm.js` since 17.0

The rounding itself needed a different approach: `get_rounding_applied()` now
reads `taxTotals.order_rounding`, only computed over payments that are already
`is_done()`. The CashDro line is still `waiting` when the amount is requested,
so a literal port would always have added 0. `getDefaultAmountDueToPayIn()` is
the 18.0 equivalent: it applies `getRoundedRemaining()` honouring both
`cash_rounding` and `only_round_cash_method`, and is what core itself uses for
the default amount of a payment line.

Only `_cashdro_payment_url()` is patched now, instead of duplicating the whole
`cashdro_send_payment_request()`, so the request flow, the acknowledge, the
polling and the error handling stay in the base module. With no cash rounding
configured the patch delegates to `super` and changes nothing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

pos_payment_method_cashdro_rounding/__init__.py

@@ -0,0 +1,2 @@
+# Copyright Criptomart
+# License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).

pos_payment_method_cashdro_rounding/__manifest__.py

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+{
+    "name": "POS CashDro Rounding",
+    "version": "18.0.1.0.0",
+    "summary": "Apply cash/currency rounding to CashDro payment request amount.",
+    "category": "Point of Sale",
+    "license": "AGPL-3",
+    "author": "Criptomart",
+    "depends": [
+        "point_of_sale",
+        "pos_payment_method_cashdro",
+    ],
+    "assets": {
+        "point_of_sale._assets_pos": [
+            "pos_payment_method_cashdro_rounding/static/src/js/cashdro_rounding.esm.js",
+        ],
+    },
+    "installable": True,
+}

pos_payment_method_cashdro_rounding/static/src/js/cashdro_rounding.esm.js

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+/* Copyright Criptomart
+   License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).
+
+   Apply the PoS cash rounding to the amount requested to the CashDro, keeping
+   the OCA integration flow untouched.
+*/
+
+import { PaymentCashdro } from "@pos_payment_method_cashdro/js/payment_cashdro.esm";
+import { patch } from "@web/core/utils/patch";
+
+patch(PaymentCashdro.prototype, {
+    /**
+     * @override
+     * The base module asks the CashDro for the plain due amount, which ignores
+     * the cash rounding configured in the PoS. As the drawer can only give back
+     * change with the coins it holds, we request the amount the customer is
+     * really expected to pay: the due amount with the cash rounding applied,
+     * which is the very same amount core defaults a payment line to.
+     *
+     * Only the url builder is patched so the rest of the payment flow of the
+     * base module (request, acknowledge, polling and error handling) is kept.
+     */
+    _cashdro_payment_url(parameters) {
+        const order = this.pos.get_order();
+        const line = order.get_selected_paymentline();
+        if (!line || !order.shouldRound(line.payment_method_id)) {
+            return super._cashdro_payment_url(...arguments);
+        }
+        // CashDro treats decimals as positions in an integer, so we round the
+        // product to avoid the trailing decimals of the floating point
+        // computation or the drawer would reject our request.
+        const amount = Math.round(
+            order.getDefaultAmountDueToPayIn(line.payment_method_id) * 100
+        );
+        return super._cashdro_payment_url({ ...parameters, amount });
+    },
+});