feat(codex-image): 封装 GPT Image 2 图片接口并收紧错误处理

- 新增 openai:image 路由、planner 与 finalize，内部通过 Codex responses image_generation tool 执行生图

- 补充 Codex OAuth/header 兼容、图片 success report 本地处理与相关前后端/集成测试

- 禁止 chat/completions 使用 gpt-image-2，图片接口限制 n=1，并移除 Provider 模型页的图片能力开关

apps/aether-gateway/src/control/route/ai.rs

@@ -30,6 +30,19 @@ pub(super) fn classify_ai_public_route(
         } else {
             Some(classified("ai_public", "openai", "cli", "openai:cli", true))
         }
+    } else if method == http::Method::POST
+        && matches!(
+            normalized_path,
+            "/v1/images/generations" | "/v1/images/edits"
+        )
+    {
+        Some(classified(
+            "ai_public",
+            "openai",
+            "image",
+            "openai:image",
+            true,
+        ))
     } else if method == http::Method::POST && normalized_path == "/v1/messages/count_tokens" {
         Some(classified(
             "ai_public",