feat: добавить уровень риска для крипто-холдингов

Риск (низкий/средний/высокий) задаётся при добавлении монеты и
редактируется прямо в таблице холдингов. Добавлена вкладка "Уровни
риска" в карточке портфеля с разбивкой % по риск-тирам, только для
крипты. Заодно поправлено округление процентов в риск-карточках.

frontend/src/components/crypto/CryptoRiskAllocationBody.tsx

@@ -0,0 +1,97 @@
+import { formatCurrency, maskAmount } from "@/lib/format";
+import { useTranslation, type TranslationKey } from "@/lib/i18n";
+import type { CryptoHolding, RiskLevel } from "@/types";
+
+interface CryptoRiskAllocationBodyProps {
+  holdings: CryptoHolding[];
+  isLoading: boolean;
+  hidden: boolean;
+}
+
+// Same status-color convention as NetWorthPage's own RiskAllocationCard
+// (low reads as "good", high as "critical") — not a categorical hue, so
+// hardcoded here rather than threaded through from the backend.
+const TIER_COLOR: Record<RiskLevel, string> = {
+  low: "var(--success)",
+  medium: "var(--text-muted)",
+  high: "var(--danger)",
+};
+const RISK_LEVELS: RiskLevel[] = ["low", "medium", "high"];
+
+/** The "Risk levels" tab's content inside CryptoOverviewCard — same
+ * three-tier layout as NetWorthPage's own RiskAllocationCard, but scoped to
+ * crypto holdings only (not the whole net worth), so "am I overweight on
+ * memecoins" doesn't get diluted by cash/real estate/etc. Entirely
+ * client-side: every holding already carries value + risk_level from
+ * GET /crypto/holdings, no separate endpoint needed. */
+export function CryptoRiskAllocationBody({ holdings, isLoading, hidden }: CryptoRiskAllocationBodyProps) {
+  const { t } = useTranslation();
+
+  if (isLoading) {
+    return <p className="py-10 text-center text-sm text-text-muted">{t("common.loading")}</p>;
+  }
+  if (holdings.length === 0) {
+    return <p className="py-10 text-center text-sm text-text-muted">{t("crypto.empty")}</p>;
+  }
+
+  // Unpriced holdings (CoinGecko never successfully priced them yet) can't
+  // contribute a % of portfolio value — same "best data on hand" principle
+  // the rest of the Crypto tab already follows for a null value/price.
+  const priced = holdings.filter((h) => h.value !== null);
+  const totalValue = priced.reduce((sum, h) => sum + Number(h.value), 0);
+
+  const tiers = RISK_LEVELS.map((level) => {
+    const items = priced
+      .filter((h) => h.risk_level === level)
+      .map((h) => ({ symbol: h.symbol, name: h.name, value: Number(h.value) }))
+      .sort((a, b) => b.value - a.value);
+    const tierValue = items.reduce((sum, item) => sum + item.value, 0);
+    return {
+      level,
+      value: tierValue,
+      percent: totalValue > 0 ? (tierValue / totalValue) * 100 : 0,
+      items: items.map((item) => ({
+        ...item,
+        percent: tierValue > 0 ? (item.value / tierValue) * 100 : 0,
+      })),
+    };
+  });
+
+  return (
+    <div className="grid grid-cols-1 gap-3 sm:grid-cols-3">
+      {tiers.map((tier) => (
+        <div key={tier.level} className="rounded-lg border border-border p-3.5">
+          <p className="flex items-center gap-1.5 text-xs font-semibold uppercase tracking-wide text-text-muted">
+            <span className="h-2 w-2 shrink-0 rounded-full" style={{ backgroundColor: TIER_COLOR[tier.level] }} />
+            {t(`netWorth.riskLevel.${tier.level}` as TranslationKey)}
+          </p>
+          <p className="mt-1.5 text-xl font-semibold tabular-nums text-text-primary">
+            {maskAmount(formatCurrency(tier.value), hidden)}
+          </p>
+          <p className="mt-1 text-xs text-text-muted">
+            {tier.percent.toFixed(1)}% {t("crypto.riskAllocationOfPortfolio")}
+          </p>
+
+          {tier.items.length > 0 && (
+            <ul className="mt-3 space-y-1.5 border-t border-gridline pt-3">
+              {tier.items.map((item) => (
+                <li key={item.symbol} className="flex items-center gap-2">
+                  <span className="min-w-0 flex-1 truncate text-xs text-text-secondary">{item.symbol}</span>
+                  <span className="h-1 w-10 shrink-0 overflow-hidden rounded-full bg-surface-2">
+                    <span
+                      className="block h-full rounded-full"
+                      style={{ width: `${item.percent}%`, backgroundColor: TIER_COLOR[tier.level] }}
+                    />
+                  </span>
+                  <span className="w-8 shrink-0 text-right text-[11px] tabular-nums text-text-muted">
+                    {item.percent.toFixed(1)}%
+                  </span>
+                </li>
+              ))}
+            </ul>
+          )}
+        </div>
+      ))}
+    </div>
+  );
+}