refactor(agent): 将 tools 模块拆分为独立文件并优化导入路径

将 `tools.ts` 拆分为按功能划分的独立文件，并存放于 `tools/` 目录下，同时更新导入路径；优化 agent 系统提示语，移除冗余的「美图 Agent」前缀。

web/server/agent/tools/create-account.ts

@@ -0,0 +1,34 @@
+import { execSync } from 'child_process';
+import { PIPELINE_SCRIPT, PROJECT_ROOT } from './shared';
+import type { ToolDefinition } from './types';
+
+export const createAccount: ToolDefinition = {
+  name: 'create_account',
+  description: '创建新的短视频账号。需要提供账号ID、名称和描述。创建后可在 accounts/ 目录下找到配置。',
+  input_schema: {
+    type: 'object',
+    properties: {
+      id: { type: 'string', description: '账号唯一标识，英文小写，如 military-account' },
+      name: { type: 'string', description: '账号显示名称，中文，如 军事账号' },
+      desc: { type: 'string', description: '账号描述，说明视频风格和主题' },
+      imageModel: { type: 'string', description: '生图模型: gemini, mj, gpt, kling' },
+      videoModel: { type: 'string', description: '视频模型: veo3-fast, veo3-fast-frames, kling, grok' },
+      format: { type: 'string', description: '画幅: 9:16 (竖屏), 16:9 (横屏), 1:1 (方形)' },
+    },
+    required: ['id', 'name'],
+  },
+  execute: async (params) => {
+    const { id, name, desc, imageModel, videoModel, format } = params as Record<string, string>;
+    const cmd = [
+      `node "${PIPELINE_SCRIPT}" create-account`,
+      `--id "${id}"`,
+      `--name "${name}"`,
+      `--desc "${desc || ''}"`,
+      `--video-model ${videoModel || 'veo3-fast'}`,
+      imageModel ? `--image-model ${imageModel}` : '',
+      format ? `--format ${format}` : '',
+    ].filter(Boolean).join(' ');
+    const result = execSync(cmd, { cwd: PROJECT_ROOT, encoding: 'utf-8' });
+    return `账号「${name}」创建成功。\n${result}`;
+  },
+};