[app-server][core] Add connector-level Guardian reviewer overrides (#25167)

Context: https://openai.slack.com/archives/C0B4JAF0Q2C/p1779912328647229

```
approvals_reviewer = "auto_review"

[apps.connector_5f3c8c41a1e54ad7a76272c89e2554fa]
enabled = true
approvals_reviewer = "user"
default_tools_approval_mode = "prompt"
```

<img width="230" height="84" alt="Screenshot 2026-05-31 at 11 56 34 AM"
src="https://github.com/user-attachments/assets/e319f8f7-0983-42a7-98cd-3302732fa406"
/>

<img width="841" height="233" alt="Screenshot 2026-05-31 at 11 52 42 AM"
src="https://github.com/user-attachments/assets/7ac76645-4e90-4d00-8242-f031146a22a5"
/>

-------

```
approvals_reviewer = "user"

[apps.connector_5f3c8c41a1e54ad7a76272c89e2554fa]
enabled = true
approvals_reviewer = "auto_review"
default_tools_approval_mode = "prompt"
```
<img width="195" height="83" alt="Screenshot 2026-05-31 at 12 02 27 PM"
src="https://github.com/user-attachments/assets/3d374dc8-8aa2-466f-a13f-e4ed8567aa2e"
/>
<img width="771" height="207" alt="Screenshot 2026-05-31 at 12 05 42 PM"
src="https://github.com/user-attachments/assets/105c2575-68d6-4ca6-8e69-dc8c82da36a2"
/>



## Summary
- add `apps.<connector_id>.approvals_reviewer` to override Guardian or
user review routing per connected app
- apply overrides across direct app MCP calls, delegated MCP prompts,
and app-server MCP elicitation review while preserving global behavior
for non-app MCP servers
- expose and document the config through app-server v2 and generated
schemas, while honoring global managed reviewer requirements

---------

Co-authored-by: jif-oai <jif@openai.com>

codex-rs/codex-mcp/src/mcp/mod.rs

@@ -21,7 +21,6 @@ use codex_config::Constrained;
 use codex_config::McpServerConfig;
 use codex_config::McpServerTransportConfig;
 use codex_config::types::AppToolApproval;
-use codex_config::types::ApprovalsReviewer;
 use codex_config::types::OAuthCredentialsStoreMode;
 use codex_login::CodexAuth;
 use codex_plugin::PluginCapabilitySummary;
@@ -91,7 +90,6 @@ pub fn mcp_permission_prompt_is_auto_approved(
 
 #[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
 pub struct McpPermissionPromptAutoApproveContext {
-    pub approvals_reviewer: Option<ApprovalsReviewer>,
     pub tool_approval_mode: Option<AppToolApproval>,
 }
 

codex-rs/codex-mcp/src/mcp/mod_tests.rs

@@ -1,7 +1,6 @@
 use super::*;
 use codex_config::Constrained;
 use codex_config::types::AppToolApproval;
-use codex_config::types::ApprovalsReviewer;
 use codex_login::CodexAuth;
 use codex_plugin::AppConnectorId;
 use codex_plugin::PluginCapabilitySummary;
@@ -96,7 +95,6 @@ fn mcp_prompt_auto_approval_honors_approved_tools_in_all_permission_modes() {
             approval_policy,
             &PermissionProfile::read_only(),
             McpPermissionPromptAutoApproveContext {
-                approvals_reviewer: Some(ApprovalsReviewer::User),
                 tool_approval_mode: Some(AppToolApproval::Approve),
             },
         ));
@@ -106,7 +104,6 @@ fn mcp_prompt_auto_approval_honors_approved_tools_in_all_permission_modes() {
         AskForApproval::OnRequest,
         &PermissionProfile::read_only(),
         McpPermissionPromptAutoApproveContext {
-            approvals_reviewer: Some(ApprovalsReviewer::AutoReview),
             tool_approval_mode: Some(AppToolApproval::Auto),
         },
     ));
@@ -118,7 +115,6 @@ fn mcp_prompt_auto_approval_rejects_auto_mode_in_default_permission_mode() {
         AskForApproval::OnRequest,
         &PermissionProfile::read_only(),
         McpPermissionPromptAutoApproveContext {
-            approvals_reviewer: Some(ApprovalsReviewer::User),
             tool_approval_mode: Some(AppToolApproval::Auto),
         },
     ));