Support multi-environment apply_patch selection (#21617)

## Summary
- add multi-environment apply_patch routing for both freeform and
function-call tool flows
- parse and reconcile the optional environment selector in the main
apply_patch parser, then verify against the selected environment in the
handler
- carry environment_id through runtime and approval surfaces so
remote-targeted patches stay explicit end to end

## Testing
- just fmt
- remote exec-server e2e: `cargo test -p codex-core --test all
apply_patch_multi_environment_uses_remote_executor -- --nocapture` on
dev via `scripts/test-remote-env.sh`

---------

Co-authored-by: Codex <noreply@openai.com>

codex-rs/apply-patch/src/lib.rs

@@ -26,6 +26,7 @@ pub use streaming_parser::StreamingPatchParser;
 use thiserror::Error;
 
 pub use invocation::maybe_parse_apply_patch_verified;
+pub use invocation::verify_apply_patch_args;
 pub use standalone_executable::main;
 
 use crate::invocation::ExtractHeredocError;
@@ -97,6 +98,7 @@ pub struct ApplyPatchArgs {
     pub patch: String,
     pub hunks: Vec<Hunk>,
     pub workdir: Option<String>,
+    pub environment_id: Option<String>,
 }
 
 #[derive(Debug, PartialEq)]