fix(presale): EVMPurchasePanel - 修复ERC/BEP网络未连接钱包时金额输入框不显示的Bug

问题描述：
- ERC/BEP面板在钱包未连接时直接早期返回，导致金额输入框不显示
- TRC面板始终显示金额输入框，造成用户体验不一致

修复方案：
- 移除EVMPurchasePanel中的早期返回（if !wallet.isConnected）
- 改为条件渲染：金额输入框和代币预览始终显示
- 钱包未连接时：在购买按钮位置显示连接钱包组件
- 错误网络时：顶部显示切换网络提示，购买按钮隐藏
- 钱包已连接且网络正确时：显示钱包信息和购买按钮

测试结果：
- BSC/ETH/TRON三个网络均在未连接钱包状态下显示金额输入框
- 构建成功，已部署到AI服务器(43.224.155.27)
- 服务已重启，trc-ico.newassetchain.io 已更新

presale-app/client/src/pages/Home.tsx

@@ -357,44 +357,7 @@ function EVMPurchasePanel({ network, lang, wallet }: { network: "BSC" | "ETH"; l
     }
   }, [purchaseState.step, purchaseState.error, purchaseState.tokenAmount, lang]);
 
-  if (!wallet.isConnected) {
+    if (purchaseState.step === "success") {
-    return (
-      <div className="space-y-4">
-        <p className="text-sm text-white/60 text-center">{t("buy_connect_msg")}</p>
-        <WalletSelector
-          lang={lang}
-          connectedAddress={wallet.address ?? undefined}
-          onAddressDetected={(addr) => {
-            // WalletSelector already called eth_requestAccounts and got the address
-            // Just show success toast; wallet state will auto-update via accountsChanged event
-            toast.success(lang === "zh" ? `已连接: ${addr.slice(0, 6)}...${addr.slice(-4)}` : `Connected: ${addr.slice(0, 6)}...${addr.slice(-4)}`);
-          }}
-          compact
-        />
-        <div className="text-xs text-white/40 text-center">{t("buy_connect_hint")}</div>
-      </div>
-    );
-  }
-
-  if (isWrongNetwork) {
-    return (
-      <div className="space-y-4">
-        <div className="rounded-xl p-4 text-center" style={{ background: "rgba(240,180,41,0.08)", border: "1px solid rgba(240,180,41,0.3)" }}>
-          <div className="text-3xl mb-2">⚠️</div>
-          <p className="text-amber-300 font-semibold mb-1">{t("buy_wrong_network")}</p>
-          <p className="text-white/60 text-sm mb-4">{t("buy_wrong_msg")} {CONTRACTS[network].chainName}</p>
-          <button
-            onClick={() => wallet.switchNetwork(targetChainId)}
-            className="btn-primary-nac px-6 py-2 rounded-lg text-sm font-bold"
-          >
-            {t("buy_switch")} {network === "BSC" ? "BSC" : "Ethereum"}
-          </button>
-        </div>
-      </div>
-    );
-  }
-
-  if (purchaseState.step === "success") {
     return (
       <div className="space-y-4 text-center py-4">
         <div className="text-5xl mb-3">🎉</div>
@@ -425,16 +388,32 @@ function EVMPurchasePanel({ network, lang, wallet }: { network: "BSC" | "ETH"; l
 
   return (
     <div className="space-y-4">
-      {/* Wallet info */}
+      {/* Wallet info — only shown when connected */}
-      <div className="flex items-center justify-between px-3 py-2 rounded-lg" style={{ background: "rgba(255,255,255,0.04)", border: "1px solid rgba(255,255,255,0.08)" }}>
+      {wallet.isConnected && !isWrongNetwork && (
-        <div className="flex items-center gap-2">
+        <div className="flex items-center justify-between px-3 py-2 rounded-lg" style={{ background: "rgba(255,255,255,0.04)", border: "1px solid rgba(255,255,255,0.08)" }}>
-          <div className="w-2 h-2 rounded-full bg-green-400" style={{ boxShadow: "0 0 6px #00e676" }} />
+          <div className="flex items-center gap-2">
-          <span className="text-xs text-white/60 counter-digit">{shortenAddress(wallet.address || "")}</span>
+            <div className="w-2 h-2 rounded-full bg-green-400" style={{ boxShadow: "0 0 6px #00e676" }} />
+            <span className="text-xs text-white/60 counter-digit">{shortenAddress(wallet.address || "")}</span>
+          </div>
+          {usdtBalance !== null && (
+            <span className="text-xs text-white/50">{t("buy_balance")} <span className="text-white/80 counter-digit">{usdtBalance.toFixed(2)} USDT</span></span>
+          )}
         </div>
-        {usdtBalance !== null && (
+      )}
-          <span className="text-xs text-white/50">{t("buy_balance")} <span className="text-white/80 counter-digit">{usdtBalance.toFixed(2)} USDT</span></span>
+      {/* Wrong network banner */}
-        )}
+      {isWrongNetwork && (
-      </div>
+        <div className="rounded-xl p-4 text-center" style={{ background: "rgba(240,180,41,0.08)", border: "1px solid rgba(240,180,41,0.3)" }}>
+          <div className="text-3xl mb-2">⚠️</div>
+          <p className="text-amber-300 font-semibold mb-1">{t("buy_wrong_network")}</p>
+          <p className="text-white/60 text-sm mb-4">{t("buy_wrong_msg")} {CONTRACTS[network].chainName}</p>
+          <button
+            onClick={() => wallet.switchNetwork(targetChainId)}
+            className="btn-primary-nac px-6 py-2 rounded-lg text-sm font-bold"
+          >
+            {t("buy_switch")} {network === "BSC" ? "BSC" : "Ethereum"}
+          </button>
+        </div>
+      )}
 
       {/* USDT Amount Input */}
       <div className="space-y-2">
@@ -502,19 +481,34 @@ function EVMPurchasePanel({ network, lang, wallet }: { network: "BSC" | "ETH"; l
         </div>
       )}
 
-      {/* Buy Button */}
+      {/* Buy Button — or Connect Wallet if not connected */}
-      <button
+      {!wallet.isConnected ? (
-        onClick={handleBuy}
+        <div className="space-y-3">
-        disabled={isProcessing || !isValidAmount}
+          <p className="text-sm text-white/60 text-center">{t("buy_connect_msg")}</p>
-        className="btn-primary-nac w-full py-4 rounded-xl text-base font-bold"
+          <WalletSelector
-        style={{ fontFamily: "'Space Grotesk', sans-serif" }}
+            lang={lang}
-      >
+            connectedAddress={wallet.address ?? undefined}
-        {isProcessing
+            onAddressDetected={(addr) => {
-          ? purchaseState.step === "approving" ? t("buy_approving")
+              toast.success(lang === "zh" ? `已连接: ${addr.slice(0, 6)}...${addr.slice(-4)}` : `Connected: ${addr.slice(0, 6)}...${addr.slice(-4)}`);
-          : purchaseState.step === "approved" ? t("buy_approved")
+            }}
-          : t("buy_processing")
+            compact
-          : `${t("buy_btn")} ${formatNumber(tokenAmount)} XIC`}
+          />
-      </button>
+          <div className="text-xs text-white/40 text-center">{t("buy_connect_hint")}</div>
+        </div>
+      ) : isWrongNetwork ? null : (
+        <button
+          onClick={handleBuy}
+          disabled={isProcessing || !isValidAmount}
+          className="btn-primary-nac w-full py-4 rounded-xl text-base font-bold"
+          style={{ fontFamily: "'Space Grotesk', sans-serif" }}
+        >
+          {isProcessing
+            ? purchaseState.step === "approving" ? t("buy_approving")
+            : purchaseState.step === "approved" ? t("buy_approved")
+            : t("buy_processing")
+            : `${t("buy_btn")} ${formatNumber(tokenAmount)} XIC`}
+        </button>
+      )}
 
       <p className="text-xs text-center text-white/30">
         {PRESALE_CONFIG.maxPurchaseUSDT > 0