_CuaDriverSession._call_tool_via_cli() (the EAGAIN/silent-empty MCP
fallback transport) invokes `cua-driver call <tool> <json>` via
subprocess.run() with no env= argument, so the third-party cua-driver
binary inherits the full, unsanitized parent environment. The primary
MCP spawn site (_lifecycle_coro) already applies
_sanitize_subprocess_env(cua_driver_child_env()) before opening the
stdio client, per the same policy #53503/#55709 established for other
subprocess spawn points — this fallback path, added alongside the
EAGAIN/silent-empty-capture hardening, missed it.
Fix: apply the same env=_sanitize_subprocess_env(cua_driver_child_env())
to the subprocess.run() call in _call_tool_via_cli(), mirroring the
sanctioned spawn site exactly (telemetry policy applied first, then
Hermes-managed secrets filtered).
