refactor: 清理未使用的类型定义和接口字段

- 移除 Provider 相关的 apiKeyEnvVar 字段（未实现的功能）
- 清理 Server routes 中未使用的 Core 类型导入
- 清理 UI Message 接口中未使用的 metadata 字段

packages/server/src/routes/agents.ts

@@ -9,7 +9,6 @@ import { getConfig } from './config.js';
 import type {
   AgentMode,
   AgentInfo,
-  AgentConfigFile,
   AgentModelConfig,
   AgentPermission,
 } from '@ai-assistant/core';

packages/server/src/routes/checkpoints.ts

@@ -6,20 +6,7 @@
 
 import { Hono } from 'hono';
 import { getConfig } from './config.js';
-import type {
-  CheckpointMetadata,
-  CheckpointConfig,
-  CheckpointTrigger,
-  FileChange,
-  FileChangeType,
-  DiffInfo,
-  FileDiff,
-  RollbackOptions,
-  RollbackResult,
-  RollbackRecord,
-  SafetyCheckResult,
-  UnrevertResult,
-} from '@ai-assistant/core';
+import type { CheckpointMetadata } from '@ai-assistant/core';
 import {
   CheckpointManager,
   getCheckpointManager,

packages/server/src/routes/commands.ts

@@ -7,11 +7,7 @@
 import { Hono } from 'hono';
 import { z } from 'zod';
 import { getConfig } from './config.js';
-import type {
-  Command,
-  CommandInput,
-  CommandExecutionResult,
-} from '@ai-assistant/core';
+// Command, CommandInput, CommandExecutionResult 类型由函数自动推断
 import {
   getCommandRegistry,
   createCommandExecutor,

packages/server/src/routes/lsp.ts

@@ -6,10 +6,7 @@
 
 import { Hono } from 'hono';
 import { getConfig } from './config.js';
-import type {
-  FileDiagnostic,
-  ServerStatus,
-} from '@ai-assistant/core';
+import type { FileDiagnostic } from '@ai-assistant/core';
 import {
   initLSP,
   listServers,

packages/server/src/routes/mcp.ts

@@ -6,12 +6,7 @@
 
 import { Hono } from 'hono';
 import { getConfig } from './config.js';
-import type {
-  MCPConfig,
-  MCPServerConfig,
-  MCPServerStatus,
-  MCPTool,
-} from '@ai-assistant/core';
+import type { MCPConfig } from '@ai-assistant/core';
 import {
   getMCPManager,
   loadMCPConfig,

packages/server/src/routes/services.ts

@@ -5,7 +5,7 @@
  */
 
 import { Hono } from 'hono';
-import type { ServiceConfig, ServiceType } from '@ai-assistant/core';
+import type { ServiceType } from '@ai-assistant/core';
 import {
   loadProvidersConfig,
   getServiceConfig,

packages/server/src/routes/sessions.ts

@@ -11,7 +11,7 @@ import {
   type Message,
   type MessagePart,
 } from '../types.js';
-import type { MessageInfo, Part, ApiPart } from '@ai-assistant/core';
+// MessageInfo, Part, ApiPart 从 Core 导入但仅用于类型推导
 import { MessageStorage, PartStorage, partsToApiFormat } from '@ai-assistant/core';
 
 export const sessionsRouter = new Hono();

packages/server/src/types.ts

@@ -365,11 +365,6 @@ export interface Message {
   parts: MessagePart[];
   /** 所有文本拼接（兼容字段） */
   content?: string;
-  metadata?: {
-    model?: string;
-    stepCount?: number;
-    totalTokens?: number;
-  };
 }
 
 /** @deprecated 使用 Message 代替 */