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/trips.ts

@@ -176,13 +176,11 @@ export default async function tripsRoutes(
         end_km: Number(body.end_km),
         route_from: String(body.route_from),
         route_to: String(body.route_to),
-        is_business:
-          !!body.is_business,
+        is_business: !!body.is_business,
         notes: body.notes ? String(body.notes) : null,
       },
     });
 
-    // Update vehicle actual_km
     await prisma.vehicles.update({
       where: { id: Number(body.vehicle_id) },
       data: { actual_km: Number(body.end_km) },
@@ -227,9 +225,7 @@ export default async function tripsRoutes(
       if (body.route_from !== undefined)
         data.route_from = String(body.route_from);
       if (body.route_to !== undefined) data.route_to = String(body.route_to);
-      if (body.is_business !== undefined)
-        data.is_business =
-          !!body.is_business;
+      if (body.is_business !== undefined) data.is_business = !!body.is_business;
       if (body.notes !== undefined)
         data.notes = body.notes ? String(body.notes) : null;