Add Lottie global loading overlay and fix stuck loading states.

Replace per-VC activity indicators with a ref-counted GlobalLoadingManager, and resolve duplicate show/hide calls on Profile, Statistics, and Home tabs.

Co-authored-by: Cursor <cursoragent@cursor.com>

suixinkan/UI/Loading/LottieLoadingView.swift

@@ -0,0 +1,51 @@
+//
+//  LottieLoadingView.swift
+//  suixinkan
+//
+
+import Lottie
+import SnapKit
+import UIKit
+
+/// Lottie 循环 Loading 动画视图，使用 `Resources/Lottie/loading.json`。
+final class LottieLoadingView: UIView {
+
+    private let animationView: LottieAnimationView
+
+    override init(frame: CGRect) {
+        animationView = LottieLoadingView.makeAnimationView()
+        super.init(frame: frame)
+        addSubview(animationView)
+        animationView.snp.makeConstraints { make in
+            make.edges.equalToSuperview()
+        }
+    }
+
+    @available(*, unavailable)
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+
+    /// 开始循环播放。
+    func startAnimating() {
+        animationView.loopMode = .loop
+        animationView.play()
+    }
+
+    /// 停止播放。
+    func stopAnimating() {
+        animationView.stop()
+    }
+
+    private static func makeAnimationView() -> LottieAnimationView {
+        if let url = loadingAnimationURL() {
+            return LottieAnimationView(filePath: url.path)
+        }
+        return LottieAnimationView()
+    }
+
+    private static func loadingAnimationURL() -> URL? {
+        Bundle.main.url(forResource: "loading", withExtension: "json", subdirectory: "Resources/Lottie")
+            ?? Bundle.main.url(forResource: "loading", withExtension: "json")
+    }
+}