* Fix flaky shard snapshot API CI readiness race
Run the prebuilt binary and poll /readyz instead of cargo run + fixed sleep, which can miss startup when cargo recompiles.
* Move shard snapshot API CI runner into a dedicated script
Keep workflow YAML thin by starting Qdrant, waiting for /readyz, and invoking shard-snapshot-api.sh from tests/shard-snapshot-api-tests.sh.