A second mod-host LV2 worker fails to start (resp -503) when LV2_DIR is the whole tests/ directory #105

Found while adding the LV2 steps to CI (#100, PR #104). With LV2_DIR set to the whole tests/ directory, the second mod-host worker fails to start with resp -503 (local run, mod-host 0.10.6.f14a230-11.1.fmx). A world holding only the fixture bundle passes, so CI uses that. Cause not found yet: likely another bundle or stray .ttl under tests/ that mod-host's lilv world refuses, but that is a guess. Reproduce: run make test-jack with LV2_DIR=$PWD/tests instead of the copied bundle directory.