feat(admin): normalize Persian/Arabic digits in every numeric field

Users typing on a Persian keyboard produced two distinct failures. Fields with
type="number" silently returned an empty string — the browser rejects Persian
digits, so the value was lost and saved as empty or zero. Text fields passed the
Persian characters straight through to the database, where a mobile stored as
۰۹۱۲… never matches 09… again. The secretary form hit the second case with no
validation at all.

Frontend:
- Adds digitsOnly() and the national-code schemas to lib/utils, plus lib/forms
  with numericField()/latinDigitsField() wrappers for React Hook Form fields.
- Converts every type="number" input to type="text" inputMode="numeric" with
  digit normalization; none remain. Fields that legitimately carry non-digits
  (sheba, landline) only get the digits translated, keeping IR and separators.
- Points the patient national-code and mobile schemas at the shared normalizing
  schemas, which accept Persian input instead of rejecting it.
- Drops two duplicate local digit converters in favour of the shared helper.

Backend:
- Adds NumericFieldNormalizerSubscriber, translating digits in whitelisted
  numeric keys of JSON request bodies under /api/v1/ before controllers run, so
  nobat724_front and clinic-pro-tauri are covered too. Translation only — no
  characters are stripped, non-string values and other keys are untouched.

Three component tests asserted on role="spinbutton" and numeric input values;
both are properties of type="number", so they were updated to match the new
text inputs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

assets/admin/pages/StaffPage.tsx

@@ -15,6 +15,7 @@ import ConfirmDialog from '../components/ui/ConfirmDialog';
 import PageHeader from '../components/ui/PageHeader';
 import SettingsLayout from '../components/layout/SettingsLayout';
 import { ActiveBadge } from '../components/ui/StatusBadge';
+import { numericField } from '../lib/forms';
 
 const schema = z.object({
   full_name: z.string().min(2, 'نام حداقل ۲ کاراکتر باید باشد'),
@@ -262,11 +263,11 @@ function StaffFormFields({ form }: { form: ReturnType<typeof useForm<StaffFormDa
       <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12 }}>
         <div className="field">
           <label>تلفن</label>
-          <input {...register('phone')} placeholder="09121234567" dir="ltr" />
+          <input {...numericField(register('phone'), 11)} placeholder="09121234567" />
         </div>
         <div className="field">
           <label>کد ملی</label>
-          <input {...register('national_code')} placeholder="0012345678" dir="ltr" />
+          <input {...numericField(register('national_code'), 10)} placeholder="0012345678" />
         </div>
       </div>
       <div className="field">