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/dashboard.ts

@@ -2,6 +2,7 @@ import { FastifyInstance } from "fastify";
 import prisma from "../../config/database";
 import { requireAuth } from "../../middleware/auth";
 import { success } from "../../utils/response";
+import { localTimeStr } from "../../utils/date";
 
 export default async function dashboardRoutes(
   fastify: FastifyInstance,
@@ -106,9 +107,7 @@ export default async function dashboardRoutes(
           name: `${user.first_name} ${user.last_name}`,
           initials: `${firstInitial}${lastInitial}`.toUpperCase(),
           status,
-          arrived_at: a.arrival_time
-            ? `${String(a.arrival_time.getHours()).padStart(2, "0")}:${String(a.arrival_time.getMinutes()).padStart(2, "0")}`
-            : null,
+          arrived_at: a.arrival_time ? localTimeStr(a.arrival_time) : null,
         });
       }
 
@@ -252,7 +251,7 @@ export default async function dashboardRoutes(
         entity_type: log.entity_type ?? "",
         description: log.description ?? "",
         username: log.username ?? null,
-        created_at: log.created_at ? log.created_at.toISOString() : "",
+        created_at: log.created_at ?? "",
       }));
     }