refactor(agent): 迁移AI会话引擎至pi-agent-core库

将原有基于Anthropic/OpenAI SDK的直播聊天代理重构为使用`@earendil-works/pi-agent-core`和`@earendil-works/pi-ai`库的统一API。

新增pi-bridge、pi-model、pi-persist、pi-tools四个模块，封装Agent路由、模型配置、消息持久化和工具适配逻辑。移除`chat.ts`中大量死代码，简化WebSocket处理流程。

BREAKING CHANGE: 移除`VideoAgent`类的`getAnthropicClient`、`getOpenAIClient`、`executeTool`等方法，外部调用需迁移至新pi-bridge API。`PROJECT_ROOT`路径计算方式变更，从`../../..`变为`../../`。

web/server/agent/index.ts

@@ -1,102 +1,12 @@
-import Anthropic from '@anthropic-ai/sdk';
-import OpenAI from 'openai';
-import { tools, ToolDefinition } from './tools/index';
-import { getDb } from '../db';
 import fs from 'fs';
 import path from 'path';
 import { fileURLToPath } from 'url';
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
-const PROJECT_ROOT = path.resolve(__dirname, '..', '..', '..', '..');
-
-export type Protocol = 'anthropic' | 'openai';
-
-interface ApiConfig {
-  protocol: Protocol;
-  apiKey: string;
-  baseURL: string | undefined;
-  model: string;
-}
-
-function getApiConfig(): ApiConfig {
-  const configRow = getDb().prepare('SELECT value FROM configs WHERE key = ?').get('api_keys') as { value: string } | undefined;
-
-  let apiKey = process.env.ANTHROPIC_API_KEY || '';
-  let baseURL: string | undefined;
-  let model = process.env.ANTHROPIC_MODEL || 'claude-sonnet-4-6';
-  let protocol: Protocol = 'anthropic';
-
-  if (configRow) {
-    try {
-      const cfg = JSON.parse(configRow.value);
-      if (cfg.ANTHROPIC_AUTH_TOKEN) apiKey = cfg.ANTHROPIC_AUTH_TOKEN;
-      if (cfg.ANTHROPIC_BASE_URL) baseURL = cfg.ANTHROPIC_BASE_URL;
-      if (cfg.ANTHROPIC_MODEL) model = cfg.ANTHROPIC_MODEL;
-      if (cfg.PROTOCOL === 'openai') protocol = 'openai';
-    } catch {}
-  }
-
-  return { protocol, apiKey, baseURL, model };
-}
-
-function getAnthropicClient(): Anthropic {
-  const { apiKey, baseURL } = getApiConfig();
-  return new Anthropic({ apiKey, baseURL });
-}
-
-function getOpenAIClient(): OpenAI {
-  const { apiKey, baseURL } = getApiConfig();
-  return new OpenAI({ apiKey, baseURL: baseURL || 'https://api.openai.com/v1' });
-}
+const PROJECT_ROOT = path.resolve(__dirname, '..', '..', '..');
 
 export class VideoAgent {
-  private tools: ToolDefinition[];
-
-  constructor() {
-    this.tools = tools;
-  }
-
-  getProtocol(): Protocol {
-    return getApiConfig().protocol;
-  }
-
-  getModel(): string {
-    return getApiConfig().model;
-  }
-
-  getAnthropicClient(): Anthropic {
-    return getAnthropicClient();
-  }
-
-  getOpenAIClient(): OpenAI {
-    return getOpenAIClient();
-  }
-
-  getAnthropicTools(): Anthropic.Tool[] {
-    return this.tools.map((t) => ({
-      name: t.name,
-      description: t.description,
-      input_schema: t.input_schema,
-    }));
-  }
-
-  getOpenAITools(): OpenAI.ChatCompletionTool[] {
-    return this.tools.map((t) => ({
-      type: 'function' as const,
-      function: {
-        name: t.name,
-        description: t.description,
-        parameters: t.input_schema,
-      },
-    }));
-  }
-
-  async executeTool(name: string, params: Record<string, unknown>): Promise<string> {
-    const tool = this.tools.find((t) => t.name === name);
-    if (!tool) throw new Error(`Unknown tool: ${name}`);
-    return tool.execute(params);
-  }
 
   getSystemPrompt(): string {
     const accountsDir = path.join(PROJECT_ROOT, 'accounts');