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/AdminSubscriptionPage.tsx

@@ -13,6 +13,7 @@ import Modal from '../components/ui/Modal';
 import ConfirmDialog from '../components/ui/ConfirmDialog';
 import PageHeader from '../components/ui/PageHeader';
 import Pagination from '../components/ui/Pagination';
+import { numericField } from '../lib/forms';
 
 // ── Types ─────────────────────────────────────────────────────────────────
 
@@ -271,11 +272,11 @@ function PlansTab() {
             <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12 }}>
               <div className="field">
                 <label>سطح *</label>
-                <input {...planForm.register('level')} type="number" min={0} dir="ltr" />
+                <input {...numericField(planForm.register('level'))} />
               </div>
               <div className="field">
                 <label>حداکثر منشی *</label>
-                <input {...planForm.register('max_secretaries')} type="number" min={1} dir="ltr" />
+                <input {...numericField(planForm.register('max_secretaries'))} />
               </div>
             </div>
             <div>
@@ -320,17 +321,17 @@ function PlansTab() {
             <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12 }}>
               <div className="field">
                 <label>مدت (ماه) *</label>
-                <input {...periodForm.register('duration_months')} type="number" min={1} dir="ltr" />
+                <input {...numericField(periodForm.register('duration_months'))} />
               </div>
               <div className="field">
                 <label>قیمت (ریال) *</label>
-                <input {...periodForm.register('price_rials')} type="number" min={0} dir="ltr" />
+                <input {...numericField(periodForm.register('price_rials'))} />
               </div>
             </div>
             <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12 }}>
               <div className="field">
                 <label>ترتیب نمایش</label>
-                <input {...periodForm.register('sort_order')} type="number" min={0} dir="ltr" />
+                <input {...numericField(periodForm.register('sort_order'))} />
               </div>
             </div>
             <div style={{ display: 'flex', gap: 16 }}>