cli.py's load_cli_config() builds CLI_CONFIG independently of
hermes_cli.config._load_config_impl (it reads config.yaml directly and merges
into hardcoded defaults), so the Phase 2 managed merge never reached the
interactive CLI/TUI surface. Symptom: a managed display.skin (and any other
display/CLI pref read from CLI_CONFIG) was silently ignored by the TUI while
`hermes config`/`doctor`/write-guards — which go through load_config — correctly
honored it. Found via manual testing: the skin engine kept using 'default'.
Fix: overlay the managed config last in load_cli_config(), mirroring
_load_config_impl — expand against the process env only (so a user ${VAR} can't
shadow a managed literal), normalize the root model key so a managed
`model: x/y` string can't clobber the dict shape callers expect, then
leaf-merge. Fail-open so managed scope can never block CLI startup.
Adds tests/hermes_cli/test_managed_scope_cli_config.py locking that CLI_CONFIG
honors managed values, preserves user siblings, and is inert with no scope.
