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/core/src/connectors.rs

@@ -43,6 +43,7 @@ use codex_mcp::codex_apps_tools_cache_key;
 use codex_mcp::compute_auth_statuses;
 use codex_mcp::effective_mcp_servers;
 use codex_mcp::host_owned_codex_apps_enabled;
+use codex_mcp::tool_plugin_provenance;
 
 const CONNECTORS_READY_TIMEOUT_ON_EMPTY_TOOLS: Duration = Duration::from_secs(30);
 
@@ -251,7 +252,8 @@ pub async fn list_accessible_connectors_from_mcp_tools_with_mcp_manager(
         });
     }
     let cache_key = accessible_connectors_cache_key(config, auth.as_ref());
-    let tool_plugin_provenance = mcp_manager.tool_plugin_provenance(config).await;
+    let mcp_config = mcp_manager.runtime_config(config).await;
+    let tool_plugin_provenance = tool_plugin_provenance(&mcp_config);
     if !force_refetch && let Some(cached_connectors) = read_cached_accessible_connectors(&cache_key)
     {
         let cached_connectors = codex_connectors::filter::filter_disallowed_connectors(
@@ -265,7 +267,6 @@ pub async fn list_accessible_connectors_from_mcp_tools_with_mcp_manager(
         });
     }
 
-    let mcp_config = mcp_manager.runtime_config(config).await;
     let mut mcp_servers = effective_mcp_servers(&mcp_config, auth.as_ref());
     mcp_servers.retain(|name, _| name == CODEX_APPS_MCP_SERVER_NAME);
     let host_owned_codex_apps_enabled = host_owned_codex_apps_enabled(&mcp_config, auth.as_ref());