Scope MCP sandbox metadata to server environment (#28914)

Scope MCP sandbox metadata to the MCP server's owning environment.

Previously, `codex/sandbox-state-meta` always used the turn's primary
cwd and rebuilt a legacy sandbox policy from that cwd. That can be wrong
for MCP servers owned by a different execution environment.

This now sends the owning environment cwd as a `file:` URI in
`sandboxCwd`, keeps `permissionProfile` as the permission source of
truth, and omits sandbox-state metadata when a non-default server
environment is not selected for the turn. Local/default MCP servers keep
the existing fallback cwd behavior.

Tests:
- `just fmt`
- `just bazel-lock-update`
- `just bazel-lock-check`
- `just test -p codex-mcp`
- `just test -p codex-core mcp_sandbox_cwd`
- `cargo build -p codex-rmcp-client --bin test_stdio_server`
- `just test -p codex-core
stdio_mcp_tool_call_includes_sandbox_state_meta`

codex-rs/codex-mcp/src/server.rs

@@ -75,6 +75,7 @@ impl McpServerOrigin {
 /// Semantic metadata that must survive after the server is launched.
 #[derive(Debug, Clone)]
 pub(crate) struct McpServerMetadata {
+    pub environment_id: String,
     pub pollutes_memory: bool,
     pub origin: Option<McpServerOrigin>,
     pub supports_parallel_tool_calls: bool,
@@ -96,6 +97,7 @@ impl From<&EffectiveMcpServer> for McpServerMetadata {
     fn from(server: &EffectiveMcpServer) -> Self {
         match server.launch() {
             McpServerLaunch::Configured(config) => Self {
+                environment_id: config.environment_id.clone(),
                 pollutes_memory: true,
                 origin: McpServerOrigin::from_transport(&config.transport),
                 supports_parallel_tool_calls: config.supports_parallel_tool_calls,