feat(pay): points-to-VIP exchange and remaining-days upgrade pricing

Add pay_vip_points_exchange packages (level|points|days|title), REST redeem
for non-VIP users, unit|daily upgrade product for residual VIP1 days, and UI.

assets/js/credits.js

@@ -318,7 +318,49 @@
 	}
 
 
-	// ===== VIP 开通 =====
+	
+	// ===== VIP 积分兑换 =====
+	function initVipPointsExchange() {
+		var root = document.querySelector('[data-aksrt-vip-points]');
+		if (!root) return;
+		var tip = root.querySelector('[data-aksrt-vip-points-tip]');
+		var busy = false;
+		function setTip(text, isError) {
+			if (!tip) return;
+			tip.textContent = text || '';
+			tip.classList.toggle('is-error', !!isError);
+		}
+		root.addEventListener('click', function (e) {
+			var btn = e.target.closest('[data-aksrt-vip-points-buy]');
+			if (!btn || busy || btn.disabled) return;
+			e.preventDefault();
+			var packageId = parseInt(btn.getAttribute('data-package-id') || '0', 10);
+			if (!packageId) return;
+			busy = true;
+			btn.classList.add('is-loading');
+			setTip('正在兑换…');
+			api('/pay/vip/points-exchange', {
+				method: 'POST',
+				body: JSON.stringify({ package_id: packageId })
+			}).then(function (r) {
+				busy = false;
+				btn.classList.remove('is-loading');
+				if (!r.ok || (r.json && r.json.code && !r.json.success)) {
+					setTip((r.json && r.json.message) || '兑换失败', true);
+					return;
+				}
+				var data = (r.json && r.json.data) ? r.json.data : r.json;
+				setTip((data && data.message) || '兑换成功，正在刷新…');
+				window.location.reload();
+			}).catch(function () {
+				busy = false;
+				btn.classList.remove('is-loading');
+				setTip('网络错误，请重试', true);
+			});
+		});
+	}
+
+// ===== VIP 开通 =====
 	function initVipShop() {
 		var root = document.querySelector('[data-aksrt-vip-shop]');
 		if (!root) return;
@@ -405,10 +447,12 @@
 			initSignin();
 			initInvite();
 			initVipShop();
+		initVipPointsExchange();
 		});
 	} else {
 		initSignin();
 		initInvite();
 		initVipShop();
+		initVipPointsExchange();
 	}
 })();