feat: v1.2.8 - Codex双Agent、图片上传、主题系统、会话加载优化

- Codex双Agent接入：共享后端内核，前台隔离会话/设置/导入
- 图片上传：Claude (stream-json) 和 Codex (--image) 均支持拖拽/粘贴/选择上传
- 主题系统：CoolVibe Light 视觉方案，主题入口移至二级页
- 会话加载优化：加载遮罩、热会话缓存、切后台内容不丢失
- 移动端增强：侧栏手势、运行状态标签、按钮比例修复
- 后端重构：agent-runtime.js / codex-rollouts.js 模块拆分
- 回归脚本：npm run regression 隔离式测试

scripts/mock-codex.js

@@ -0,0 +1,62 @@
+#!/usr/bin/env node
+
+const crypto = require('crypto');
+
+function readStdin() {
+  return new Promise((resolve) => {
+    let data = '';
+    process.stdin.setEncoding('utf8');
+    process.stdin.on('data', (chunk) => { data += chunk; });
+    process.stdin.on('end', () => resolve(data));
+  });
+}
+
+(async function main() {
+  const args = process.argv.slice(2);
+  const isResume = args[0] === 'exec' && args[1] === 'resume';
+  const threadId = isResume && args[2] ? args[2] : `mock-${crypto.randomUUID()}`;
+  const input = (await readStdin()).trim();
+  const imageCount = args.filter((arg) => arg === '--image').length;
+
+  process.stdout.write(`${JSON.stringify({ type: 'thread.started', thread_id: threadId })}\n`);
+  process.stdout.write(`${JSON.stringify({ type: 'turn.started' })}\n`);
+
+  if (/pwd/i.test(input)) {
+    process.stdout.write(`${JSON.stringify({
+      type: 'item.started',
+      item: {
+        id: 'item_cmd',
+        type: 'command_execution',
+        command: '/bin/bash -lc pwd',
+        aggregated_output: '',
+        exit_code: null,
+        status: 'in_progress',
+      },
+    })}\n`);
+    process.stdout.write(`${JSON.stringify({
+      type: 'item.completed',
+      item: {
+        id: 'item_cmd',
+        type: 'command_execution',
+        command: '/bin/bash -lc pwd',
+        aggregated_output: '/tmp/mock-codex\n',
+        exit_code: 0,
+        status: 'completed',
+      },
+    })}\n`);
+  }
+
+  process.stdout.write(`${JSON.stringify({
+    type: 'item.completed',
+    item: {
+      id: 'item_msg',
+      type: 'agent_message',
+      text: `Codex mock handled (${imageCount} image): ${input}`,
+    },
+  })}\n`);
+
+  process.stdout.write(`${JSON.stringify({
+    type: 'turn.completed',
+    usage: { input_tokens: 10, cached_input_tokens: 2, output_tokens: 5 },
+  })}\n`);
+})();