v1.6.8: remove offer exchange rate, add invoice item description, offer filters, table animations

- Remove exchange_rate and exchange_rate_date from quotations (schema, service, PDF, form)
- Add item_description field to invoice_items (schema, migration, service, form, PDF)
- Add offer status/customer/order filters with tab-based UI
- Clean up offer statuses to active/ordered/invalidated
- Allow invalidate action for non-ordered offers (not just expired)
- Add fade animations on offers and invoices table data changes

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/routes/admin/invoices-pdf.ts

@@ -450,10 +450,11 @@ export default async function invoicesPdfRoutes(
             const lineVat = applyVat ? (lineSubtotal * vatRate) / 100 : 0;
             const lineTotal = lineSubtotal + lineVat;
             const qtyDecimals = Math.floor(qty) === qty ? 0 : 2;
+            const subDesc = item.item_description || "";
 
             return `<tr>
             <td class="row-num">${i + 1}</td>
-            <td class="desc">${escapeHtml(item.description)}</td>
+            <td class="desc">${escapeHtml(item.description)}${subDesc ? `<div class="item-subdesc">${escapeHtml(subDesc)}</div>` : ""}</td>
             <td class="center">${formatNum(qty, qtyDecimals)}${item.unit ? ` / ${escapeHtml(item.unit)}` : ""}</td>
             <td class="right">${formatNum(unitPrice)}</td>
             <td class="right">${formatNum(lineSubtotal)}</td>
@@ -693,6 +694,11 @@ export default async function invoicesPdfRoutes(
     font-weight: 600;
     color: #1a1a1a;
   }
+  .item-subdesc {
+    font-size: 9pt;
+    color: #646464;
+    margin-top: 2px;
+  }
   table.items tbody td.total-cell { font-weight: 700; }
 
   /* Soucet + total - styl z nabidek */