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/tui/src/chatwidget/tests/exec_flow.rs

@@ -10,6 +10,7 @@ async fn exec_approval_emits_proposed_command_and_decision_history() {
         call_id: "call-short".into(),
         approval_id: Some("call-short".into()),
         turn_id: "turn-short".into(),
+        environment_id: None,
         command: vec!["bash".into(), "-lc".into(), "echo hello world".into()],
         cwd: AbsolutePathBuf::current_dir().expect("current dir"),
         reason: Some(
@@ -56,6 +57,7 @@ fn app_server_exec_approval_request_splits_shell_wrapped_command() {
             item_id: "item-1".to_string(),
             started_at_ms: 0,
             approval_id: Some("approval-1".to_string()),
+            environment_id: None,
             reason: None,
             network_approval_context: None,
             command: Some(
@@ -93,6 +95,7 @@ async fn exec_approval_uses_approval_id_when_present() {
             call_id: "call-parent".into(),
             approval_id: Some("approval-subcommand".into()),
             turn_id: "turn-short".into(),
+            environment_id: None,
             command: vec!["bash".into(), "-lc".into(), "echo hello world".into()],
             cwd: AbsolutePathBuf::current_dir().expect("current dir"),
             reason: Some(
@@ -136,6 +139,7 @@ async fn exec_approval_decision_truncates_multiline_and_long_commands() {
         call_id: "call-multi".into(),
         approval_id: Some("call-multi".into()),
         turn_id: "turn-multi".into(),
+        environment_id: None,
         command: vec!["bash".into(), "-lc".into(), "echo line1\necho line2".into()],
         cwd: AbsolutePathBuf::current_dir().expect("current dir"),
         reason: Some(
@@ -189,6 +193,7 @@ async fn exec_approval_decision_truncates_multiline_and_long_commands() {
         call_id: "call-long".into(),
         approval_id: Some("call-long".into()),
         turn_id: "turn-long".into(),
+        environment_id: None,
         command: vec!["bash".into(), "-lc".into(), long],
         cwd: AbsolutePathBuf::current_dir().expect("current dir"),
         reason: None,
@@ -1098,6 +1103,7 @@ async fn approval_modal_exec_snapshot() -> anyhow::Result<()> {
         call_id: "call-approve-cmd".into(),
         approval_id: Some("call-approve-cmd".into()),
         turn_id: "turn-approve-cmd".into(),
+        environment_id: None,
         command: vec!["bash".into(), "-lc".into(), "echo hello world".into()],
         cwd: AbsolutePathBuf::current_dir().expect("current dir"),
         reason: Some(
@@ -1155,6 +1161,7 @@ async fn approval_modal_exec_without_reason_snapshot() -> anyhow::Result<()> {
         call_id: "call-approve-cmd-noreason".into(),
         approval_id: Some("call-approve-cmd-noreason".into()),
         turn_id: "turn-approve-cmd-noreason".into(),
+        environment_id: None,
         command: vec!["bash".into(), "-lc".into(), "echo hello world".into()],
         cwd: AbsolutePathBuf::current_dir().expect("current dir"),
         reason: None,
@@ -1201,6 +1208,7 @@ async fn approval_modal_exec_multiline_prefix_hides_execpolicy_option_snapshot()
         call_id: "call-approve-cmd-multiline-trunc".into(),
         approval_id: Some("call-approve-cmd-multiline-trunc".into()),
         turn_id: "turn-approve-cmd-multiline-trunc".into(),
+        environment_id: None,
         command: command.clone(),
         cwd: AbsolutePathBuf::current_dir().expect("current dir"),
         reason: None,