feat: add Cost and Margin % columns with inline editing

Cost column shows Odoo standard_price (editable). Margin % is calculated
from cost and sale price. Editing margin auto-calculates the sale price
using: price = cost / (1 - margin/100). All cells are inline-editable.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

fusion-woo-odoo/fusion_woocommerce/static/src/js/product_mapping.js

@@ -226,6 +226,19 @@ export class ProductMapping extends Component {
         return "$" + n.toFixed(2);
     }
 
+    calcMargin(cost, price) {
+        const c = parseFloat(cost) || 0;
+        const p = parseFloat(price) || 0;
+        if (p <= 0 || c <= 0) return null;
+        return ((p - c) / p) * 100;
+    }
+
+    formatMargin(cost, price) {
+        const m = this.calcMargin(cost, price);
+        if (m === null) return "—";
+        return m.toFixed(1) + "%";
+    }
+
     // -------------------------------------------------------------------------
     // Tab handlers
     // -------------------------------------------------------------------------
@@ -606,6 +619,44 @@ export class ProductMapping extends Component {
                         kwargs: {},
                     });
                 }
+            } else if (cell.field === 'odoo_cost') {
+                const product = this.state.mappedProducts.find(p => p.id === cell.mapId);
+                if (product && product.odoo_product_id) {
+                    await rpc("/web/dataset/call_kw", {
+                        model: "product.product",
+                        method: "write",
+                        args: [[product.odoo_product_id], { standard_price: value }],
+                        kwargs: {},
+                    });
+                }
+            } else if (cell.field === 'margin') {
+                // Margin edit: calculate new sale price from cost and desired margin
+                const product = this.state.mappedProducts.find(p => p.id === cell.mapId);
+                if (product && product.odoo_product_id) {
+                    const cost = parseFloat(product.odoo_cost) || 0;
+                    if (cost <= 0) {
+                        this.notification.add("Cannot calculate price: cost is zero.", { type: "danger" });
+                        await this._loadMapped();
+                        return;
+                    }
+                    if (value >= 100) {
+                        this.notification.add("Margin cannot be 100% or more.", { type: "danger" });
+                        await this._loadMapped();
+                        return;
+                    }
+                    // price = cost / (1 - margin/100)
+                    const newPrice = cost / (1 - value / 100);
+                    const rounded = Math.round(newPrice * 100) / 100;
+                    await rpc("/web/dataset/call_kw", {
+                        model: "product.product",
+                        method: "write",
+                        args: [[product.odoo_product_id], { list_price: rounded }],
+                        kwargs: {},
+                    });
+                    this.notification.add("Sale price set to $" + rounded.toFixed(2) + " (" + value.toFixed(1) + "% margin).", { type: "success" });
+                    await this._loadMapped();
+                    return;
+                }
             }
             this.notification.add("Price updated.", { type: "success" });
         } catch (err) {