refactor: 将 codex provider 转换工具迁移至 @ant/model-provider 包

将纯转换工具（callIds、modelMapping、convertMessages、convertTools）
从 src/services/api/codex/ 迁移到 packages/@ant/model-provider/src/providers/codex/，
与 OpenAI/Gemini/Grok provider 保持一致的代码组织模式。同时修复了
streaming.test.ts 中缺失的 mock 导出（logAntError、context 常量、langfuse 导出）。

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

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

@@ -0,0 +1,39 @@
+function getModelFamily(model: string): 'haiku' | 'sonnet' | 'opus' | null {
+  if (/haiku/i.test(model)) return 'haiku'
+  if (/opus/i.test(model)) return 'opus'
+  if (/sonnet/i.test(model)) return 'sonnet'
+  return null
+}
+
+export function resolveCodexModel(model: string): string {
+  if (process.env.CODEX_MODEL) {
+    return process.env.CODEX_MODEL
+  }
+
+  const cleanModel = model.replace(/\[1m\]$/, '')
+  const family = getModelFamily(cleanModel)
+  if (family) {
+    const familyOverride = process.env[`CODEX_DEFAULT_${family.toUpperCase()}_MODEL`]
+    if (familyOverride) {
+      return familyOverride
+    }
+  }
+
+  return cleanModel
+}
+
+export function resolveCodexMaxTokens(
+  upperLimit: number,
+  maxOutputTokensOverride?: number,
+): number {
+  return (
+    maxOutputTokensOverride ??
+    (process.env.CODEX_MAX_TOKENS
+      ? parseInt(process.env.CODEX_MAX_TOKENS, 10) || undefined
+      : undefined) ??
+    (process.env.CLAUDE_CODE_MAX_OUTPUT_TOKENS
+      ? parseInt(process.env.CLAUDE_CODE_MAX_OUTPUT_TOKENS, 10) || undefined
+      : undefined) ??
+    upperLimit
+  )
+}