feat: TypeScript + Electron v2 重构 - 纯桌面版

- 全面迁移到 TypeScript，严格类型定义
- 放弃 Web 版，专注 Electron 桌面应用
- 主进程模块化：main.ts, preload.ts, menu.ts, tray.ts, ipc.ts, utils.ts
- 渲染进程完整迁移所有功能组件
- 删除 PWA 相关文件 (sw.js, manifest.json)
- 删除 Web 版降级逻辑
- 保留所有核心功能：流式对话、多模型、Think推理、多模态、RAG知识库、Agent预设、历史管理
- 保留 Windows 11 Fluent Design 暗色主题样式

src/renderer/services/document-processor.ts

@@ -0,0 +1,74 @@
+/**
+ * DocumentProcessor - 文档分块处理
+ */
+
+export function chunkText(text: string, { maxChunkSize = 1500, overlap = 200 } = {}): string[] {
+  if (!text || text.trim().length === 0) return [];
+
+  const paragraphs = text.split(/\n\s*\n/).filter(p => p.trim());
+  const chunks: string[] = [];
+  let current = '';
+
+  for (const para of paragraphs) {
+    const trimmed = para.trim();
+    if (!trimmed) continue;
+
+    if (trimmed.length > maxChunkSize) {
+      if (current) {
+        chunks.push(current.trim());
+        current = '';
+      }
+      const sentences = splitSentences(trimmed);
+      let sentenceBuf = '';
+      for (const sent of sentences) {
+        if ((sentenceBuf + sent).length > maxChunkSize && sentenceBuf) {
+          chunks.push(sentenceBuf.trim());
+          sentenceBuf = overlap > 0 ? sentenceBuf.slice(-overlap) + sent : sent;
+        } else {
+          sentenceBuf += sent;
+        }
+      }
+      if (sentenceBuf.trim()) {
+        current = sentenceBuf;
+      }
+      continue;
+    }
+
+    if ((current + '\n\n' + trimmed).length > maxChunkSize && current) {
+      chunks.push(current.trim());
+      if (overlap > 0 && current.length > overlap) {
+        current = current.slice(-overlap) + '\n\n' + trimmed;
+      } else {
+        current = trimmed;
+      }
+    } else {
+      current = current ? current + '\n\n' + trimmed : trimmed;
+    }
+  }
+
+  if (current.trim()) {
+    chunks.push(current.trim());
+  }
+
+  return chunks;
+}
+
+function splitSentences(text: string): string[] {
+  const parts = text.split(/(?<=[。！？.!?])\s*/);
+  return parts.filter(p => p.trim()).map(p => p.trim() + ' ');
+}
+
+export function extractDocument(content: string, filename: string): { text: string; filename: string } {
+  return { text: content, filename };
+}
+
+export function createChunkMetadata(chunk: string, index: number, docId: string, filename: string) {
+  return {
+    id: `${docId}_chunk_${index}`,
+    docId,
+    filename,
+    chunkIndex: index,
+    text: chunk,
+    charCount: chunk.length
+  };
+}