feat: initial implementation of Focus RSVP speed reader

- Pure frontend SPA (Vite + React 19 + TypeScript + Tailwind CSS v4)
- Spritz ORP engine with absolute center crosshair gaze fixation
- Multilingual hybrid segmentation via Intl.Segmenter with punctuation attachment
- Adaptive breathing rhythm delay algorithm for natural comprehension
- IndexedDB local bookshelf, progress persistence, and client-side EPUB/TXT/MD parsing
- Curated sci-fi, philosophy, and classic speech samples
- Dark/OLED/Sepia/Slate/Nord themes and rich keyboard controls

Co-Authored-By: Claude Code <noreply@anthropic.com>

src/core/epub.ts

@@ -0,0 +1,148 @@
+import JSZip from 'jszip';
+import type { Chapter } from '../types';
+
+export interface ParsedEpub {
+  title: string;
+  author: string;
+  fullText: string;
+  chapters: Chapter[];
+}
+
+export async function parseEpubFile(file: File | Blob): Promise<ParsedEpub> {
+  const arrayBuffer = await file.arrayBuffer();
+  const zip = await JSZip.loadAsync(arrayBuffer);
+
+  // 1. Locate container.xml
+  const containerXmlFile = zip.file('META-INF/container.xml');
+  if (!containerXmlFile) {
+    throw new Error('无效的 EPUB 格式：缺少 META-INF/container.xml');
+  }
+
+  const containerXml = await containerXmlFile.async('text');
+  const domParser = new DOMParser();
+  const containerDoc = domParser.parseFromString(containerXml, 'application/xml');
+  const rootfileEl = containerDoc.querySelector('rootfile');
+  const opfPath = rootfileEl?.getAttribute('full-path');
+
+  if (!opfPath) {
+    throw new Error('无法在 container.xml 中找到 OPF 元数据路径');
+  }
+
+  // 2. Read OPF file
+  const opfFile = zip.file(opfPath);
+  if (!opfFile) {
+    throw new Error(`无法找到 OPF 文件：${opfPath}`);
+  }
+
+  const opfDir = opfPath.includes('/') ? opfPath.substring(0, opfPath.lastIndexOf('/') + 1) : '';
+  const opfXml = await opfFile.async('text');
+  const opfDoc = domParser.parseFromString(opfXml, 'application/xml');
+
+  // Metadata
+  const title = opfDoc.querySelector('title, dc\\:title')?.textContent?.trim() || (file instanceof File ? file.name.replace(/\.epub$/i, '') : '未命名书籍');
+  const author = opfDoc.querySelector('creator, dc\\:creator')?.textContent?.trim() || '未知作者';
+
+  // Manifest: id -> href
+  const manifestMap = new Map<string, string>();
+  opfDoc.querySelectorAll('manifest > item').forEach((item) => {
+    const id = item.getAttribute('id');
+    const href = item.getAttribute('href');
+    if (id && href) {
+      // Decode URL encoding
+      manifestMap.set(id, decodeURIComponent(href));
+    }
+  });
+
+  // Spine: ordered list of itemrefs
+  const spineItemIds: string[] = [];
+  opfDoc.querySelectorAll('spine > itemref').forEach((itemref) => {
+    const idref = itemref.getAttribute('idref');
+    if (idref) {
+      spineItemIds.push(idref);
+    }
+  });
+
+  const chapters: Chapter[] = [];
+  let fullText = '';
+  let chapterIndex = 1;
+
+  for (const idref of spineItemIds) {
+    const relativeHref = manifestMap.get(idref);
+    if (!relativeHref) continue;
+
+    // Resolve full path inside zip
+    const filePath = opfDir ? resolvePath(opfDir, relativeHref) : relativeHref;
+    const chapterFile = zip.file(filePath);
+    if (!chapterFile) continue;
+
+    const contentHtml = await chapterFile.async('text');
+    const chapterDoc = domParser.parseFromString(contentHtml, 'text/html');
+
+    // Extract title from headings or title tag
+    const heading = chapterDoc.querySelector('h1, h2, h3, title');
+    let chapterTitle = heading?.textContent?.trim() || '';
+    if (!chapterTitle || chapterTitle.length > 50) {
+      chapterTitle = `第 ${chapterIndex} 节`;
+    }
+
+    // Extract text content cleanly
+    const body = chapterDoc.body || chapterDoc.documentElement;
+    // Remove scripts and styles
+    body.querySelectorAll('script, style, svg').forEach((el) => el.remove());
+
+    const paragraphs: string[] = [];
+    const elements = body.querySelectorAll('p, h1, h2, h3, h4, h5, h6, li, blockquote');
+
+    if (elements.length > 0) {
+      elements.forEach((el) => {
+        const text = el.textContent?.trim();
+        if (text) paragraphs.push(text);
+      });
+    } else {
+      const text = body.textContent?.trim();
+      if (text) paragraphs.push(text);
+    }
+
+    const chapterText = paragraphs.join('\n\n');
+    if (chapterText.trim().length > 0) {
+      chapters.push({
+        id: `chap-${chapterIndex}`,
+        title: chapterTitle,
+        startIndex: fullText.length,
+      });
+
+      fullText += (fullText ? '\n\n' : '') + chapterText;
+      chapterIndex++;
+    }
+  }
+
+  if (!fullText.trim()) {
+    throw new Error('未能从 EPUB 提取到可读文本');
+  }
+
+  return {
+    title,
+    author,
+    fullText,
+    chapters,
+  };
+}
+
+/**
+ * Resolves a relative path against a base directory.
+ */
+function resolvePath(baseDir: string, relativePath: string): string {
+  const parts = (baseDir + relativePath).split('/');
+  const resolved: string[] = [];
+
+  for (const part of parts) {
+    if (part === '.' || part === '') continue;
+    if (part === '..') {
+      resolved.pop();
+    } else {
+      resolved.push(part);
+    }
+  }
+
+  return resolved.join('/');
+}