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/components/ServiceInsuranceModal.tsx

@@ -127,7 +127,7 @@ function ContractCard({ contract, item }: { contract: TenantInsurance; item: Ser
                 <div style={{ minWidth: 0 }}>
                   <label className="field-label">درصد پوشش</label>
                   <input
-                    type="number" min={0} max={100} dir="ltr" className="input"
+                    type="text" inputMode="numeric" dir="ltr" className="input"
                     style={{ height: 40, textAlign: 'left' }}
                     value={draft.coverage_percent ?? ''}
                     placeholder="ارث"