[codex] Load API curated marketplace by auth (#28383)

## Summary
- choose the local OpenAI curated marketplace manifest based on auth:
Codex backend auth gets the existing marketplace, direct provider auth
gets `api_marketplace.json`
- include Bedrock API key auth in the direct-provider API marketplace
path
- safely skip the API marketplace when `api_marketplace.json` is absent

## Validation
- `just fmt`
- `git diff --check origin/main...HEAD`
- CI should run the full validation

## Manual Testing

### - New api marketplace not available for API key sign
1. Safely not display anything from api marketplace
<img width="1161" height="289" alt="Screenshot 2026-06-15 at 21 37 43"
src="https://github.com/user-attachments/assets/a5f16642-8a20-4ac1-a0de-1274a4c7b5b2"
/>

### - New api marketplace for API key sign in
1. Setup api_marketplace.json
```
{
  "name": "openai-curated",
  "interface": {
    "displayName": "Codex official"
  },
  "plugins": [
    {
      "name": "linear",
      "source": {
        "source": "local",
        "path": "./plugins/linear"
      },
      "policy": {
        "installation": "AVAILABLE",
        "authentication": "ON_INSTALL"
      },
      "category": "Productivity"
    }
  ]
}
```

2. Log in with API key, observe that only the defined plugin from
api_marketplace.json is available from "Codex Official" (outside of
local testing marketplaces)
<img width="1167" height="446" alt="Screenshot 2026-06-15 at 21 16 53"
src="https://github.com/user-attachments/assets/7cf61477-d826-4ef6-bc05-0a23ac1c0259"
/>

also checked functionality on codex app

### - SiWC users 
Still uses 'default' marketplace.json and renders all plugins
<img width="1171" height="502" alt="Screenshot 2026-06-15 at 21 40 25"
src="https://github.com/user-attachments/assets/d212ea9b-0aa5-470b-8ea4-450efe65bb2b"
/>

also checked functionality on codex app


## Notes
- `just test -p codex-core-plugins` was started locally before splitting
branches, but I stopped relying on local tests per follow-up and left
final validation to PR CI.

codex-rs/core-plugins/src/test_support.rs

@@ -1,6 +1,7 @@
 use std::fs;
 use std::path::Path;
 
+use crate::OPENAI_API_CURATED_MARKETPLACE_NAME;
 use crate::OPENAI_CURATED_MARKETPLACE_NAME;
 use crate::PluginsConfigInput;
 use codex_config::LoaderOverrides;
@@ -57,6 +58,32 @@ pub(crate) fn write_curated_plugin(root: &Path, plugin_name: &str) {
 }
 
 pub(crate) fn write_openai_curated_marketplace(root: &Path, plugin_names: &[&str]) {
+    write_curated_marketplace(
+        root,
+        "marketplace.json",
+        OPENAI_CURATED_MARKETPLACE_NAME,
+        /*display_name*/ None,
+        plugin_names,
+    );
+}
+
+pub(crate) fn write_openai_api_curated_marketplace(root: &Path, plugin_names: &[&str]) {
+    write_curated_marketplace(
+        root,
+        "api_marketplace.json",
+        OPENAI_API_CURATED_MARKETPLACE_NAME,
+        Some("OpenAI Curated"),
+        plugin_names,
+    );
+}
+
+fn write_curated_marketplace(
+    root: &Path,
+    manifest_name: &str,
+    marketplace_name: &str,
+    display_name: Option<&str>,
+    plugin_names: &[&str],
+) {
     let plugins = plugin_names
         .iter()
         .map(|plugin_name| {
@@ -72,11 +99,21 @@ pub(crate) fn write_openai_curated_marketplace(root: &Path, plugin_names: &[&str
         })
         .collect::<Vec<_>>()
         .join(",\n");
+    let interface = display_name
+        .map(|display_name| {
+            format!(
+                r#"
+  "interface": {{
+    "displayName": "{display_name}"
+  }},"#
+            )
+        })
+        .unwrap_or_default();
     write_file(
-        &root.join(".agents/plugins/marketplace.json"),
+        &root.join(".agents/plugins").join(manifest_name),
         &format!(
             r#"{{
-  "name": "{OPENAI_CURATED_MARKETPLACE_NAME}",
+  "name": "{marketplace_name}",{interface}
   "plugins": [
 {plugins}
   ]