Resolve MCP server registrations through a catalog (#27634)

## Why

MCP servers currently come from user config, local plugins,
compatibility Apps synthesis, and host extensions. Those sources were
composed by mutating a shared map, leaving registration identity,
precedence, removal, and provenance implicit in assembly order.

Before adding executor-owned MCPs, Codex needs one durable resolution
boundary above `McpConnectionManager`. This PR introduces that boundary
while preserving current server configuration, policy, and runtime
behavior. Executor-scoped registrations and explicit policy layers
remain follow-ups.

## What changed

- Add typed `McpServerRegistration` inputs and an immutable
`ResolvedMcpCatalog` in `codex-mcp`.
- Retain each registration's complete `McpServerConfig`, including its
environment binding, while recording its source and provenance.
- Preserve the existing structural precedence between plugin, config,
compatibility, and ordered extension sources.
- Resolve equal-precedence actions by contribution order; provenance IDs
are used only for diagnostics and cannot affect the winner.
- Preserve extension removals and the existing name-scoped `enabled =
false` veto.
- Report same-tier conflicts with every contender and the final catalog
outcome, including whether the winning action registers or removes the
server.
- Require MCP contributors to provide a stable diagnostic identity.
- Derive materialized server maps and plugin ownership from the resolved
catalog.

`McpConnectionManager`, transport startup, tool calls, and resource
routing continue to consume the same effective `McpServerConfig` values.

## Scope

This PR does not add new MCP capabilities or change user-visible
behavior. It does not add executor plugin discovery, thread-scoped
registrations, dynamic refresh generations, or new user/managed policy
semantics.

## Verification

- Added focused catalog coverage for source precedence, complete
configuration preservation, disabled vetoes, plugin ownership,
contribution-order tie breaking, removal outcomes, and conflict
diagnostics.
- Extended hosted Apps coverage for ordered extension removal and
Apps-disabled hosts with and without the hosted extension installed.
- `cargo check -p codex-mcp --tests -p codex-extension-api -p
codex-core`

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

@@ -37,6 +37,7 @@ use rmcp::model::ReadResourceResult;
 use serde_json::Value;
 use tokio_util::sync::CancellationToken;
 
+use crate::ResolvedMcpCatalog;
 use crate::codex_apps::codex_apps_tools_cache_key;
 use crate::connection_manager::McpConnectionManager;
 use crate::runtime::McpRuntimeContext;
@@ -135,13 +136,8 @@ pub struct McpConfig {
     pub prefix_mcp_tool_names: bool,
     /// Client-side elicitation capabilities advertised during MCP initialization.
     pub client_elicitation_capability: ElicitationCapability,
-    /// Materialized MCP servers keyed by server name.
-    ///
-    /// A host may add compatibility built-ins and extension overlays before
-    /// calling runtime entry points in this crate.
-    pub configured_mcp_servers: HashMap<String, McpServerConfig>,
-    /// Winning plugin owner for plugin-provided MCP servers, keyed by server name.
-    pub plugin_ids_by_mcp_server_name: HashMap<String, String>,
+    /// Resolved MCP registrations keyed by logical server name.
+    pub mcp_server_catalog: ResolvedMcpCatalog,
     /// Plugin metadata used to attribute MCP tools/connectors to plugin display names.
     pub plugin_capability_summaries: Vec<PluginCapabilitySummary>,
 }
@@ -176,6 +172,7 @@ impl ToolPluginProvenance {
 
     fn from_config(config: &McpConfig) -> Self {
         let mut tool_plugin_provenance = Self::default();
+        let plugin_ids_by_mcp_server_name = config.mcp_server_catalog.plugin_ids_by_server_name();
         for plugin in &config.plugin_capability_summaries {
             for connector_id in &plugin.app_connector_ids {
                 tool_plugin_provenance
@@ -185,7 +182,9 @@ impl ToolPluginProvenance {
                     .push(plugin.display_name.clone());
             }
 
-            for server_name in &plugin.mcp_server_names {
+            for server_name in plugin.mcp_server_names.iter().filter(|server_name| {
+                plugin_ids_by_mcp_server_name.get(*server_name) == Some(&plugin.config_name)
+            }) {
                 tool_plugin_provenance
                     .plugin_display_names_by_mcp_server_name
                     .entry(server_name.clone())
@@ -206,8 +205,7 @@ impl ToolPluginProvenance {
             plugin_names.sort_unstable();
             plugin_names.dedup();
         }
-        tool_plugin_provenance.plugin_ids_by_mcp_server_name =
-            config.plugin_ids_by_mcp_server_name.clone();
+        tool_plugin_provenance.plugin_ids_by_mcp_server_name = plugin_ids_by_mcp_server_name;
 
         tool_plugin_provenance
     }
@@ -218,7 +216,7 @@ pub fn host_owned_codex_apps_enabled(config: &McpConfig, auth: Option<&CodexAuth
 }
 
 pub fn configured_mcp_servers(config: &McpConfig) -> HashMap<String, McpServerConfig> {
-    config.configured_mcp_servers.clone()
+    config.mcp_server_catalog.configured_servers()
 }
 
 pub fn effective_mcp_servers(