_apply_external_secret_sources() added the home to _APPLIED_HOMES before
loading config, so a malformed config.yaml, a missing secrets section, or
all-sources-disabled permanently disabled secret loading for the process
— even after the user fixed the config. Long-lived processes (gateway)
never recovered without a restart.
Now the home is marked only after apply_all() actually ran with at least
one enabled source. Fetch errors still mark the home (so import-time
load_hermes_dotenv() calls don't re-fetch and re-print the same failure
3-5x per startup); the cheap early-exit paths stay retryable.
Fixes#40597.
