feat: NAS storage for invoices/offers, code cleanup, date/time fixes

- NAS storage for created invoices (PDF via puppeteer), received invoices,
  and offers with auto-save on create/edit
- Deterministic file paths derived from DB fields (no file_path column needed)
- Separate NAS mount points: NAS_FINANCIALS_PATH, NAS_OFFERS_PATH
- Invoice language field (cs/en) stored per invoice, replaces lang modal
- Invoices list filtered by month/year matching KPI card selection
- Centralized date helpers (src/utils/date.ts) replacing all .toISOString()
  calls that returned UTC instead of local time
- Attendance project switching uses exact time (not rounded)
- Comment cleanup: removed ~100 unnecessary/Czech comments
- Removed as-any casts in orders and attendance
- Prisma migrations: add invoice language, drop received_invoices BLOB columns

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

src/admin/pages/OfferDetail.tsx

@@ -345,7 +345,6 @@ export default function OfferDetail() {
     form.valid_until &&
     new Date(form.valid_until) < new Date(new Date().toDateString());
 
-  // Load data
   const fetchDetail = useCallback(async () => {
     if (!id) return;
     try {
@@ -473,7 +472,6 @@ export default function OfferDetail() {
     }
   }, [showCustomerDropdown]);
 
-  // Fetch next quotation number for new offers
   useEffect(() => {
     if (isEdit) return;
     const fetchNextNumber = async () => {
@@ -584,7 +582,6 @@ export default function OfferDetail() {
     setItems((prev) => prev.filter((_, i) => i !== index));
   };
 
-  // Totals
   const subtotal = items.reduce((sum, item) => {
     if (item.is_included_in_total) {
       return (
@@ -624,6 +621,12 @@ export default function OfferDetail() {
       });
       const result = await response.json();
       if (result.success) {
+        const offerId = isEdit ? id : result.data?.id;
+        if (offerId) {
+          await apiFetch(`${API_BASE}/offers-pdf/${offerId}?save=1`).catch(
+            () => {},
+          );
+        }
         alert.success(
           result.message ||
             (isEdit ? "Nabídka byla aktualizována" : "Nabídka byla vytvořena"),
@@ -736,22 +739,16 @@ export default function OfferDetail() {
     if (!isEdit || pdfLoading) return;
     setPdfLoading(true);
     try {
-      const response = await apiFetch(`${API_BASE}/offers-pdf/${id}`);
+      const response = await apiFetch(`${API_BASE}/offers/${id}/file`);
       if (response.status === 401) return;
       if (!response.ok) {
-        alert.error("Nepodařilo se vygenerovat PDF");
+        alert.error("PDF soubor nenalezen — uložte nabídku pro vygenerování");
         return;
       }
-      const html = await response.text();
-      const w = window.open("", "_blank");
-      if (w) {
-        w.document.open();
-        w.document.write(html);
-        w.document.close();
-        w.onload = () => w.print();
-      } else {
-        alert.error("Prohlížeč zablokoval vyskakovací okno");
-      }
+      const blob = await response.blob();
+      const url = URL.createObjectURL(blob);
+      window.open(url, "_blank");
+      setTimeout(() => URL.revokeObjectURL(url), 60000);
     } catch {
       alert.error("Chyba při generování PDF");
     } finally {
@@ -858,29 +855,29 @@ export default function OfferDetail() {
             <button
               onClick={handlePdf}
               className="admin-btn admin-btn-secondary"
+              style={{
+                display: "inline-flex",
+                alignItems: "center",
+                gap: "0.4rem",
+              }}
               disabled={pdfLoading}
             >
               {pdfLoading ? (
-                <>
-                  <div className="admin-spinner admin-spinner-sm" />
-                  PDF...
-                </>
+                <div className="admin-spinner admin-spinner-sm" />
               ) : (
-                <>
-                  <svg
-                    width="16"
-                    height="16"
-                    viewBox="0 0 24 24"
-                    fill="none"
-                    stroke="currentColor"
-                    strokeWidth="2"
-                  >
-                    <path d="M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z" />
-                    <polyline points="14 2 14 8 20 8" />
-                  </svg>
-                  PDF
-                </>
+                <svg
+                  width="16"
+                  height="16"
+                  viewBox="0 0 24 24"
+                  fill="none"
+                  stroke="currentColor"
+                  strokeWidth="2"
+                >
+                  <path d="M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z" />
+                  <polyline points="14 2 14 8 20 8" />
+                </svg>
               )}
+              Zobrazit nabídku
             </button>
           )}
           {isEdit &&