Scope command approvals by execution environment (#28738)

## Why

Command approval cache keys included the command and working directory,
but not the execution environment. An approval for `/workspace` locally
could therefore be reused for the same command and path on an executor.

## What changed

- Include the selected environment ID in shell and unified-exec approval
cache keys.
- Carry that ID through the normal command approval request so clients
can show which environment is being approved.
- Expose the environment through app-server as a required nullable
`environmentId` and show it in the inline TUI approval prompt.
- Keep older recorded approval events compatible when the environment is
absent.

For example, `echo ok` in local `/workspace` and `echo ok` in executor
`/workspace` now produce different approval keys and separate prompts.

## Scope

This PR does not change network approvals, Guardian review actions, MCP
elicitation, full-screen TUI rendering, or environment-ID validation.
Remote `shell_command` execution itself remains in #28722; this PR only
makes its approval key environment-aware.

codex-rs/app-server/src/bespoke_event_handling.rs

@@ -550,6 +550,7 @@ pub(crate) async fn apply_bespoke_event_handling(
                 call_id,
                 approval_id,
                 turn_id,
+                environment_id,
                 started_at_ms,
                 command,
                 cwd,
@@ -626,6 +627,7 @@ pub(crate) async fn apply_bespoke_event_handling(
                 item_id: call_id.clone(),
                 started_at_ms,
                 approval_id: approval_id.clone(),
+                environment_id,
                 reason,
                 network_approval_context,
                 command,

codex-rs/app-server/src/outgoing_message.rs

@@ -977,6 +977,7 @@ mod tests {
                 item_id: "item-1".to_string(),
                 started_at_ms: 0,
                 approval_id: None,
+                environment_id: None,
                 reason: None,
                 network_approval_context: None,
                 command: Some("echo hi".to_string()),

codex-rs/app-server/src/transport_tests.rs

@@ -250,6 +250,7 @@ async fn command_execution_request_approval_strips_additional_permissions_withou
                     item_id: "call_123".to_string(),
                     started_at_ms: 0,
                     approval_id: None,
+                    environment_id: None,
                     reason: Some("Need extra read access".to_string()),
                     network_approval_context: None,
                     command: Some("cat file".to_string()),
@@ -315,6 +316,7 @@ async fn command_execution_request_approval_keeps_additional_permissions_with_ca
                     item_id: "call_123".to_string(),
                     started_at_ms: 0,
                     approval_id: None,
+                    environment_id: None,
                     reason: Some("Need extra read access".to_string()),
                     network_approval_context: None,
                     command: Some("cat file".to_string()),