v0.20 removed the code-symbol graph, but installs still carry its
leftovers:
- <data_dir>/grammars holds tree-sitter grammar libraries (~44 MB on
the audited machine) that `yams init` / `yams config grammar` built
and nothing loads any more.
- A yams_symbol_extractor plugin under the install prefix is refused on
every start with two warnings (the ABI host's skip plus the plugin
manager's "load failed"), and the refusal flipped the plugin host FSM
through Failed.
Remove the grammars once through metadata migration 43, so the cleanup
is recorded in schema_migrations and never repeats. It only acts on a
data directory's yams.db, only deletes libtree-sitter-* / tree-sitter-*
files directly in grammars/, removes the directory only when nothing
else is left in it, and leaves a symlinked grammars/ (and its target)
alone, so nothing outside the data directory can be touched.
The install prefix is not ours to clean, so the stale plugin is only
reported: one info line per process naming the file that can be
deleted. PluginManager recognises that refusal and skips it quietly
instead of warning and dispatching a load failure.
Signed-off-by: trvon <me@trevon.dev>
