ragleap-rag (Java) v0.7.0

Adds QdrantBackend — a third vector backend alongside pgvector and FaissBackend. Talks to Qdrant's plain REST API directly (no gRPC client, no new Maven dependency), with deterministic point IDs (delete-then-reinsert stability), a SQLite text sidecar, and a built-in fix for Qdrant's raw [-1,1] cosine-similarity range (normalized to [0,1] to match pgvector's convention — the same bug already found and fixed in the Python source). 16 new tests, all live against a real running Qdrant instance rather than mocked, with a connectivity-probe guard (@EnabledIf) so CI skips cleanly when no Qdrant service is available. Published to Maven Central: io.github.antonyrag:ragleap-rag:0.7.0