feat: 添加 Codex 模型 provider 完整实现

- 新增 codex API 客户端、流适配、消息/工具转换、模型映射
- 支持 CODEX_API_KEY 和 CODEX_ACCESS_TOKEN 双认证 fallback
- 集成到 claude.ts 调度链和 Langfuse 可观测性
- 包含模型映射单元测试（16 cases）

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

packages/@ant/model-provider/src/providers/codex/convertTools.ts

@@ -0,0 +1,39 @@
+import type { BetaToolUnion } from '@anthropic-ai/sdk/resources/beta/messages/messages.mjs'
+import type { Tool as CodexTool } from 'openai/resources/responses/responses.mjs'
+
+function isClientFunctionTool(
+  tool: BetaToolUnion,
+): tool is BetaToolUnion & {
+  name: string
+  description?: string
+  input_schema?: { [key: string]: unknown }
+  strict?: boolean
+  defer_loading?: boolean
+} {
+  const value = tool as unknown as Record<string, unknown>
+  return typeof value.name === 'string'
+}
+
+export function anthropicToolsToCodex(
+  tools: BetaToolUnion[],
+): CodexTool[] {
+  return tools.flatMap(tool => {
+    const value = tool as unknown as Record<string, unknown>
+    if (
+      value.type === 'advisor_20260301' ||
+      value.type === 'computer_20250124' ||
+      !isClientFunctionTool(tool)
+    ) {
+      return []
+    }
+
+    return [{
+      type: 'function',
+      name: tool.name,
+      description: tool.description,
+      parameters: tool.input_schema ?? {},
+      strict: tool.strict ?? null,
+      ...(tool.defer_loading && { defer_loading: true }),
+    }]
+  })
+}