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.rs

@@ -852,6 +852,7 @@ fn exec_approval_request_from_params(
         additional_permissions: params.additional_permissions,
         turn_id: params.turn_id,
         approval_id: params.approval_id,
+        environment_id: params.environment_id,
         proposed_execpolicy_amendment: params.proposed_execpolicy_amendment,
         proposed_network_policy_amendments: params.proposed_network_policy_amendments,
         available_decisions: params.available_decisions,