fix: remove process.cwd() fallback for working directory in chat route

The chat route and claude-client both fell back to process.cwd() when
working_directory was empty, causing Claude to operate in the server's
directory instead of the user's project. Since session creation now
requires a valid working_directory, these fallbacks are unnecessary
and misleading. Fall back to os.homedir() as a safer last resort.

Also update CLAUDE.md: require explicit user confirmation before
publishing releases (no auto push+tag).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -21,6 +21,10 @@ CodePilot — Claude Code 的桌面 GUI 客户端，基于 Electron + Next.js。
 
 **重要：不要手动创建 GitHub Release**，否则会与 CI 自动创建的 Release 冲突。如果需要本地打包测试，使用 `npm run electron:pack:mac` 但不要手动上传到 Release。
 
+## 发版纪律
+
+**禁止自动发版**：不要在完成代码修改后自动执行 `git push` + `git tag` + `git push origin tag` 发版流程。必须等待用户明确指示"发版"、"发布"或类似确认后才能执行。代码提交（commit）可以正常进行，但推送和打 tag 必须由用户确认。
+
 ## Development Rules
 
 **提交前必须详尽测试：**

src/app/api/chat/route.ts

@@ -32,7 +32,7 @@ export async function POST(request: NextRequest) {
     let savedContent = content;
     let fileMeta: Array<{ id: string; name: string; type: string; size: number; filePath: string }> | undefined;
     if (files && files.length > 0) {
-      const workDir = session.working_directory || process.cwd();
+      const workDir = session.working_directory;
       const uploadDir = path.join(workDir, '.codepilot-uploads');
       if (!fs.existsSync(uploadDir)) {
         fs.mkdirSync(uploadDir, { recursive: true });

src/lib/claude-client.ts

@@ -316,7 +316,7 @@ export function streamClaude(options: ClaudeStreamOptions): ReadableStream<strin
         const skipPermissions = getSetting('dangerously_skip_permissions') === 'true';
 
         const queryOptions: Options = {
-          cwd: workingDirectory || process.cwd(),
+          cwd: workingDirectory || os.homedir(),
           abortController,
           includePartialMessages: true,
           permissionMode: skipPermissions