fix: security, validation, and data integrity fixes across 53 files

- Auth: HS256 algorithm restriction on JWT verify, timing-safe bcrypt
  for inactive/locked users, locked_until check in loadAuthData, TOTP
  fixes (async bcrypt, BigInt conversion, future-code counter fix)
- Validation: Zod enums for leave_type/status, numeric transforms on
  foreign keys, VAT 0% coercion fix (Number(v)||21 → v!=null checks)
- Permissions: requirePermission on attendance PUT, attendance_users
  and project_logs access checks, trips users filtered by trips.record
- Prisma queries: fixed roles.is:{OR} pattern (doesn't work on to-one
  relations), attendance_users now filters by attendance.record only
- Transactions: wrapped deleteOrder, createOrder, updateUser, deleteUser,
  duplicateOffer, bulkCreateAttendance, createLeave, scope-templates,
  leave-requests, company-settings, profile updates
- Frontend: mountedRef reset in useListData, blob URL cleanup on unmount,
  null checks on date fields, AdminDatePicker min/max for HH:mm
- Security headers: COOP, CORP, CSP frame-ancestors/form-action/base-uri
- Other: exchange-rate cache TTL, invoice-alert midnight comparison fix,
  numbering.service releaseSequence no-op, nas-offers filename sanitize,
  Content-Disposition header injection fix, mojibake Czech strings

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.env.example

@@ -7,13 +7,13 @@ HOST=127.0.0.1
 APP_ENV=local
 
 # Auth — MUST regenerate for production: openssl rand -hex 32
-JWT_SECRET=generate-with-openssl-rand-hex-32
+JWT_SECRET=REPLACE_WITH_64_CHAR_HEX_STRING_RUN_openssl_rand_hex_32
 ACCESS_TOKEN_EXPIRY=900
 REFRESH_TOKEN_SESSION_EXPIRY=3600
 REFRESH_TOKEN_REMEMBER_EXPIRY=2592000
 
 # TOTP — MUST regenerate for production: openssl rand -hex 32
-TOTP_ENCRYPTION_KEY=generate-with-openssl-rand-hex-32
+TOTP_ENCRYPTION_KEY=REPLACE_WITH_64_CHAR_HEX_STRING_RUN_openssl_rand_hex_32
 
 # File storage
 NAS_PATH=Z:/02_PROJEKTY