fix: Spanish frontend, wider columns, currency symbols, PDF download

PDF fix:
- Replace session-cookie auth with HTTP Basic Auth (username:api_key)
  which is natively supported by Odoo 17+ report endpoints
- Validate response is actually a PDF (%PDF header check) before serving
- Return a descriptive Spanish error if HTTP code != 200 or body is not PDF

Frontend → Spanish:
- All invoice template text in Spanish (Nº Factura, Vencimiento, etc.)
- All calendar/booking template text in Spanish
- Payment state labels: Pendiente / Parcial / En cobro / Pagado / Anulado
- "Vencida" badge for overdue invoices
- Error/notice messages in Spanish across both pages

Currency symbols:
- Add currency_symbol() helper mapping ISO codes to symbols
- EUR → €, USD → $, GBP → £, etc. (25 currencies mapped)

Column widths:
- Switch invoice table to table-layout:fixed with explicit column widths
- col-number: 180px nowrap so reference never wraps across lines
- Date/due/amount/status columns all fixed-width and nowrap
- Add .woodoo-nowrap utility class

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

assets/css/woodoo.css

@@ -56,18 +56,35 @@
     width: 100%;
     border-collapse: collapse;
     font-size: .875rem;
+    table-layout: fixed;  /* fixed layout so column widths are respected */
 }
 .woodoo-table th,
 .woodoo-table td {
-    padding: 10px 12px;
+    padding: 10px 14px;
     border-bottom: 1px solid #e5e7eb;
     text-align: left;
     vertical-align: middle;
+    overflow: hidden;
 }
 .woodoo-table th { background: #f9fafb; font-weight: 600; }
 .woodoo-table tr:last-child td { border-bottom: none; }
-.woodoo-table .woodoo-amount { text-align: right; font-variant-numeric: tabular-nums; }
-.woodoo-table .woodoo-inv-number { font-weight: 600; }
+.woodoo-table .woodoo-amount {
+    text-align: right;
+    font-variant-numeric: tabular-nums;
+    white-space: nowrap;
+}
+/* Invoice-specific column widths */
+.woodoo-invoices-table .col-number  { width: 180px; white-space: nowrap; font-weight: 600; }
+.woodoo-invoices-table .col-date    { width: 100px; white-space: nowrap; }
+.woodoo-invoices-table .col-due     { width: 130px; }
+.woodoo-invoices-table .col-amount  { width: 110px; text-align: right; }
+.woodoo-invoices-table .col-balance { width: 130px; text-align: right; }
+.woodoo-invoices-table .col-status  { width: 100px; white-space: nowrap; }
+.woodoo-invoices-table .col-download{ width: 70px;  text-align: center; }
+
+/* Utility: never wrap content in a cell */
+.woodoo-nowrap { white-space: nowrap; }
+
 .woodoo-overdue { color: #dc2626; font-weight: 600; }
 
 /* ── Pagination ──────────────────────────────────────────── */