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/schemas/users.schema.ts

@@ -7,7 +7,10 @@ export const CreateUserSchema = z.object({
   first_name: z.string().min(1, "Jméno je povinné"),
   last_name: z.string().min(1, "Příjmení je povinné"),
   role_id: z.union([z.number(), z.string()]).transform((v) => Number(v)),
-  is_active: z.preprocess(v => v === true || v === 1 || v === "1", z.boolean()).optional().default(true),
+  is_active: z
+    .preprocess((v) => v === true || v === 1 || v === "1", z.boolean())
+    .optional()
+    .default(true),
 });
 
 export const UpdateUserSchema = z.object({
@@ -17,7 +20,9 @@ export const UpdateUserSchema = z.object({
   first_name: z.string().optional(),
   last_name: z.string().optional(),
   role_id: z.union([z.number(), z.string(), z.null()]).optional(),
-  is_active: z.preprocess(v => v === true || v === 1 || v === "1", z.boolean()).optional(),
+  is_active: z
+    .preprocess((v) => v === true || v === 1 || v === "1", z.boolean())
+    .optional(),
 });
 
 export type CreateUserInput = z.infer<typeof CreateUserSchema>;