Upgrade rmcp to 3.0.0 (#36001)

## What changed

- Update the Rust MCP SDK from `3.0.0-beta.3` to `3.0.0` and adapt to its renamed metadata and server discovery types.
- Accept discovery responses without server identity metadata, using the configured server name as a fallback, and rely on the SDK's native support for namespaced server identity metadata.
- Preserve typed OAuth HTTP errors so transport failures, cross-origin redirects, and transient HTTP responses are reported instead of being treated as anonymous access.

## Testing

- Cover modern discovery with namespaced or missing server identity over HTTP, SSE, and stdio.
- Cover OAuth discovery error propagation for transport failures, redirects, and transient status codes.

GitOrigin-RevId: 12c1e45136cca89ce4fb15986c2b5df14608682a

codex-rs/core/src/connectors_tests.rs

@@ -17,7 +17,7 @@ use codex_mcp::CODEX_APPS_MCP_SERVER_NAME;
 use codex_mcp::ToolInfo;
 use pretty_assertions::assert_eq;
 use rmcp::model::JsonObject;
-use rmcp::model::Meta;
+use rmcp::model::MetaObject;
 use rmcp::model::Tool;
 use std::collections::BTreeMap;
 use std::collections::HashSet;
@@ -150,7 +150,7 @@ fn accessible_connectors_from_mcp_tools_carries_plugin_display_names() {
 #[test]
 fn synthetic_links_are_exposed_to_the_agent_but_not_accessible_in_app_list() {
     let mut synthetic_tool = codex_app_tool("gmail_batch_read_email", "gmail", Some("Gmail"), &[]);
-    synthetic_tool.tool.meta = Some(Meta(
+    synthetic_tool.tool.meta = Some(MetaObject(
         serde_json::json!({
             "resource_name": "gmail.batch_read_email",
             "_codex_apps": {

codex-rs/core/src/mcp_tool_exposure_test.rs

@@ -7,7 +7,7 @@ use codex_tools::ToolExposure;
 use codex_tools::ToolName;
 use pretty_assertions::assert_eq;
 use rmcp::model::JsonObject;
-use rmcp::model::Meta;
+use rmcp::model::MetaObject;
 use rmcp::model::Tool;
 
 use super::*;
@@ -98,7 +98,7 @@ fn runtimes_by_name(runtimes: &[Arc<dyn CoreToolRuntime>]) -> HashMap<ToolName,
 }
 
 fn with_visibility(mut tool: ToolInfo, visibility: &[&str]) -> ToolInfo {
-    tool.tool.meta = Some(Meta(
+    tool.tool.meta = Some(MetaObject(
         serde_json::json!({ "ui": { "visibility": visibility } })
             .as_object()
             .expect("metadata object")