The left-core migration's only gate was "plugin dir missing + Home Assistant in use", so after
`hermes plugins remove homeassistant` every agent start, gateway start and `hermes update`
reinstalled and re-enabled it (~7.5 s each).
The automatic install now happens at most once per home and row: `_left_core_installed` in
config.yaml is written (in the same write as the toolset-scope marker when the plugin was already
there, right after a successful install otherwise) and only once the plugin dir exists in that
home. A marked row is never installed again; a catalog miss, failed install or lazy-installs-off
start writes nothing, so those homes keep retrying. Profile clones copy plugins/ with config.yaml,
so a clone's marker always matches what its source had.
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