feat: 内置阅读器、批注笔记与 AI 助手，发布 1.3.0

新增 PDF/EPUB/MOBI/AZW 内置阅读器，PDF 分段读取支持超大文件，
批注、读书与画布笔记、封面生成与本地导入。AI 助手支持三种协议、
图像上下文与安全 Markdown 渲染，上下文范围改为 选中/当前页/全文，
页面与全文无需选中文本即可发送，全文会提示可能超出模型限制。

便携版输出目录固定为 PeopleLib-windows-x64，不再随版本号变化，
避免升级后 data/ 被遗留在旧目录。

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

src/ui/views/browse.js

@@ -427,41 +427,118 @@ const Browse = (() => {
     };
   }
 
+  function formatBytes(value) {
+    const bytes = Math.max(0, Number(value) || 0);
+    if (bytes < 1024) return `${bytes} B`;
+    if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
+    if (bytes < 1024 * 1024 * 1024) return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
+    return `${(bytes / (1024 * 1024 * 1024)).toFixed(2)} GB`;
+  }
+
+  function createDownloadProgress(row) {
+    const box = document.createElement('div');
+    box.className = 'dl-progress';
+    const track = document.createElement('div');
+    track.className = 'dl-progress-track';
+    const fill = document.createElement('div');
+    fill.className = 'dl-progress-fill';
+    const label = document.createElement('span');
+    label.className = 'dl-progress-label';
+    label.textContent = '准备下载…';
+    track.appendChild(fill);
+    box.append(track, label);
+    row.appendChild(box);
+    return { box, fill, label };
+  }
+
+  function updateDownloadProgress(progress, data) {
+    const received = Number(data && data.receivedBytes) || 0;
+    const total = Number(data && data.totalBytes) || 0;
+    const ratio = Number(data && data.percent);
+    if (data && data.percent != null && Number.isFinite(ratio)) {
+      const percent = Math.max(0, Math.min(1, ratio));
+      progress.box.classList.remove('indeterminate');
+      progress.fill.style.width = `${Math.round(percent * 100)}%`;
+      progress.label.textContent = total
+        ? `${Math.round(percent * 100)}% · ${formatBytes(received)} / ${formatBytes(total)}`
+        : `${Math.round(percent * 100)}% · ${formatBytes(received)}`;
+    } else {
+      progress.box.classList.add('indeterminate');
+      progress.label.textContent = `${formatBytes(received)} 已下载`;
+    }
+  }
+
   async function downloadFile(btn, url) {
     const orig = btn.textContent;
+    const sourceId = state.activeSourceId;
+    const sourcePostId = state.currentPostId;
+    const meta = entryMeta();
+    const suggestedName = btn.dataset.name || '';
+    const row = btn.closest('.dl-file-row');
+    const oldProgress = row && row.querySelector('.dl-progress');
+    if (oldProgress) oldProgress.remove();
+    const progress = row ? createDownloadProgress(row) : null;
     btn.disabled = true;
     btn.textContent = '下载中...';
 
-    const lib = await window.api.library.findBySource(state.activeSourceId, state.currentPostId);
+    const lib = await window.api.library.findBySource(sourceId, sourcePostId);
     const entryId = (lib.ok && lib.data) ? lib.data.id : undefined;
     // 传 meta：条目还不在书库时由主进程自动建，避免下载完却找不到文件
-    const res = await window.api.downloadFile(url, btn.dataset.name || '', entryId, undefined, entryMeta());
+    let res;
+    try {
+      res = await window.api.downloadFile(
+        url,
+        suggestedName,
+        entryId,
+        undefined,
+        meta,
+        (data) => { if (progress) updateDownloadProgress(progress, data); }
+      );
+    } catch (error) {
+      res = { ok: false, error: (error && error.message) || String(error) };
+    }
 
     if (res.ok && res.data && res.data.canceled) {
+      if (progress) progress.box.remove();
       btn.textContent = orig; btn.disabled = false;
       return;
     }
     if (!res.ok) {
+      if (progress) {
+        progress.box.classList.add('failed');
+        progress.label.textContent = res.error || '下载失败';
+      }
       btn.textContent = '失败';
       btn.title = res.error || '';
-      setTimeout(() => { btn.textContent = orig; btn.disabled = false; }, 2000);
+      setTimeout(() => {
+        if (progress) progress.box.remove();
+        btn.textContent = orig;
+        btn.disabled = false;
+      }, 2000);
       return;
     }
 
     // 下载即入库，刷新"加入书库"按钮并就地提供打开入口
     if (window.Library) window.Library.markDirty();
-    refreshAddButton();
+    if (state.activeSourceId === sourceId && state.currentPostId === sourcePostId) {
+      refreshAddButton();
+    }
 
     const saved = res.data.path;
+    if (progress) {
+      updateDownloadProgress(progress, { ...res.data, percent: 1, complete: true });
+      progress.label.textContent = '下载完成';
+      setTimeout(() => progress.box.remove(), 900);
+    }
     btn.textContent = '打开';
+    btn.title = '打开已下载文件';
     btn.disabled = false;
-    btn.classList.add('copied');
+    btn.classList.add('downloaded');
     btn.onclick = async () => {
       const r = await window.api.openPath(saved);
       if (!r.ok) await confirmModal('打开失败', r.error || '无法打开该文件');
     };
 
-    const row = btn.closest('.dl-file-row');
     if (row && !row.querySelector('.reveal-btn')) {
       const reveal = document.createElement('button');
       reveal.className = 'copy-btn reveal-btn';