fix(salary): use median monthly salary (robust to bonus/outlier months)

Full-history check found one work month with a stray 3rd installment
(₮5.77M) skewing latest-complete and the mean. Switch the monthly-salary
figure (income card + safe-to-spend) to the median of fully-paid work
months (₮3.83M here), robust to that outlier. Card now shows a 'сарын
дундаж ~₮X' caption under salary.

src/features/home/DashboardView.tsx

@@ -252,6 +252,7 @@ function IncomeRow({ label, value, dotColor, loading, hidden }: { label: string;
 function IncomeCard({ month, loading, hidden }: { month?: Analyze; loading: boolean; hidden: boolean }) {
   const salary = dec(month?.salaryIncome);
   const support = dec(month?.otherIncome);
+  const typical = dec(month?.monthlySalary);
   const income = dec(month?.income);
   const expense = dec(month?.expense);
   const saved = income - expense;
@@ -265,6 +266,11 @@ function IncomeCard({ month, loading, hidden }: { month?: Analyze; loading: bool
       <SectionHeader title={s.incomeTitle} />
       <div style={{ display: "flex", flexDirection: "column", gap: 10 }}>
         <IncomeRow label={s.incomeSalary} value={salary} dotColor={good} loading={loading} hidden={hidden} />
+        {!loading && typical > 0 && (
+          <div style={{ fontSize: 12, color: "var(--seed-color-fg-neutral-muted, #8b8b8b)", marginTop: -6, marginLeft: 18 }}>
+            {s.incomeTypical} {hidden ? MASKED : tugrikShortRaw(typical)}
+          </div>
+        )}
         <IncomeRow label={s.incomeSupport} value={support} dotColor="var(--mercury-brand-yellow, #f2b021)" loading={loading} hidden={hidden} />
       </div>
       <div>

src/features/home/strings.ts

@@ -24,6 +24,7 @@ export const homeStrings = {
   // Income card — earned salary vs support, and what's kept.
   incomeTitle: "Энэ сарын орлого",
   incomeSalary: "Цалин",
+  incomeTypical: "сарын дундаж",
   incomeSupport: "Дэмжлэг ба бусад",
   incomeSaved: "Хэмнэсэн",
   incomeSpentOf: "зарцуулсан",