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/routes/admin/quotations.ts

@@ -19,6 +19,7 @@ import {
   invalidateOffer,
   getNextOfferNumber,
 } from "../../services/offers.service";
+import { nasOffersManager } from "../../services/nas-offers-manager";
 
 const LOCK_TIMEOUT_MS = 10 * 1000; // 10 seconds — lock expires if no heartbeat
 
@@ -122,7 +123,6 @@ export default async function quotationsRoutes(
       const data = await getOffer(id);
       if (!data) return error(reply, "Nabídka nenalezena", 404);
 
-      // Include lock info
       const quotation = await prisma.quotations.findUnique({
         where: { id },
         select: { locked_by: true, locked_at: true },
@@ -305,6 +305,14 @@ export default async function quotationsRoutes(
       const existing = await deleteOffer(id);
       if (!existing) return error(reply, "Nabídka nenalezena", 404);
 
+      // Delete PDF from NAS
+      if (existing.quotation_number && existing.created_at) {
+        const yr = new Date(existing.created_at).getFullYear();
+        nasOffersManager.deleteOfferPdf(
+          nasOffersManager.buildRelativePath(existing.quotation_number, yr),
+        );
+      }
+
       await logAudit({
         request,
         authData: request.authData,
@@ -316,4 +324,38 @@ export default async function quotationsRoutes(
       return success(reply, null, 200, "Nabídka smazána");
     },
   );
+
+  // GET /api/admin/offers/:id/file — serve PDF from NAS
+  fastify.get<{ Params: { id: string } }>(
+    "/:id/file",
+    { preHandler: requirePermission("offers.view") },
+    async (request, reply) => {
+      const id = parseId(request.params.id, reply);
+      if (id === null) return;
+      const offer = await prisma.quotations.findUnique({
+        where: { id },
+        select: { quotation_number: true, created_at: true },
+      });
+      if (!offer?.quotation_number)
+        return error(reply, "Nabídka nenalezena", 404);
+
+      const year = offer.created_at
+        ? new Date(offer.created_at).getFullYear()
+        : new Date().getFullYear();
+      const relPath = nasOffersManager.buildRelativePath(
+        offer.quotation_number,
+        year,
+      );
+      const file = nasOffersManager.readOfferPdf(relPath);
+      if (!file) return error(reply, "PDF soubor nenalezen", 404);
+
+      return reply
+        .type("application/pdf")
+        .header(
+          "Content-Disposition",
+          `inline; filename="${offer.quotation_number}.pdf"`,
+        )
+        .send(file.data);
+    },
+  );
 }