feat: 插件适配页面与系统完善（v0.1.0）

- 修复 /categories、/tags 因变量为 List 误用 .items 导致的 500
- 新增 layout.html 布局契约，消除插件页面 fallback 警告
- 适配 plugin-moments / plugin-photos / plugin-links（含友链申请表单与 RSS 订阅页）
- 适配 halo-weread-plugin（书架页）、留言板单页模板
- 适配 plugin-extra-api 的代码高亮与暗色样式
- 修复暗黑模式评论区不可见（补充 color-scheme 与兜底样式）
- 更新元数据：作者暖心向阳335、版本 0.1.0、requires >=2.26.0

src/js/post.ts

@@ -1 +1,82 @@
-console.log("Hello, Halo Theme Post!");
+/**
+ * whitespace 留白主题 - 文章页脚本
+ * 代码块复制 + 阅读进度条
+ */
+
+// ========================================
+// 代码块复制
+// ========================================
+
+function initCodeCopy(): void {
+  const codeBlocks = document.querySelectorAll<HTMLElement>(
+    ".article-content pre",
+  );
+
+  codeBlocks.forEach((pre) => {
+    const copyBtn = document.createElement("button");
+    copyBtn.className = "code-copy-btn";
+    copyBtn.type = "button";
+    copyBtn.textContent = "复制";
+
+    pre.style.position = "relative";
+    pre.appendChild(copyBtn);
+
+    copyBtn.addEventListener("click", async () => {
+      const code = pre.querySelector("code");
+      const text = code ? (code.textContent ?? "") : (pre.textContent ?? "");
+      try {
+        await navigator.clipboard.writeText(text);
+        copyBtn.textContent = "已复制";
+        copyBtn.classList.add("copied");
+        setTimeout(() => {
+          copyBtn.textContent = "复制";
+          copyBtn.classList.remove("copied");
+        }, 2000);
+      } catch {
+        console.error("复制失败");
+      }
+    });
+  });
+}
+
+// ========================================
+// 阅读进度条
+// ========================================
+
+function initReadingProgress(): void {
+  const article = document.querySelector<HTMLElement>(".article-content");
+  if (!article) return;
+
+  const progressBar = document.createElement("div");
+  progressBar.className = "reading-progress";
+  document.body.appendChild(progressBar);
+
+  const updateProgress = () => {
+    const articleTop = article.offsetTop;
+    const articleHeight = article.offsetHeight;
+    const windowHeight = window.innerHeight;
+    const scrollY = window.scrollY;
+
+    const start = articleTop - windowHeight;
+    const end = articleTop + articleHeight;
+    const current = scrollY;
+
+    let progress = ((current - start) / (end - start)) * 100;
+    progress = Math.max(0, Math.min(100, progress));
+    progressBar.style.width = `${progress}%`;
+  };
+
+  window.addEventListener("scroll", updateProgress, { passive: true });
+  updateProgress();
+}
+
+function init(): void {
+  initCodeCopy();
+  initReadingProgress();
+}
+
+if (document.readyState === "loading") {
+  document.addEventListener("DOMContentLoaded", init);
+} else {
+  init();
+}