Azure provider silently uses local compaction instead of `POST /responses/compact`

Problem

When using an Azure OpenAI provider (name = "Azure" or an Azure base URL), Codex silently falls back to local model-generated compaction instead of calling POST /responses/compact, even though Azure's Responses API fully supports it. No error or warning is shown.

Root Cause

The compaction routing gate in core/src/compact.rs checks only is_openai():

pub(crate) fn should_use_remote_compact_task(provider: &ModelProviderInfo) -> bool {
    provider.is_openai()   // true only when name == "OpenAI" (exact, case-sensitive)
}

The standard Azure configuration requires name = "Azure" to activate attach_item_ids via is_azure_responses_endpoint() (case-insensitive check in codex-api/src/provider.rs). But that same name makes is_openai() return false, silently disabling remote compaction. The two checks are mutually exclusive — no single name value satisfies both.

| name | is_openai() | is_azure_responses_endpoint() | Result |
|---|---|---|---|
| "OpenAI" | ✓ | ✗ | Remote compaction on, attach_item_ids off (breaks Azure) |
| "Azure" | ✗ | ✓ | Remote compaction off, attach_item_ids on |