fix(kb): stop DROP INDEX killing HNSW via Ladybug ghost catalog

Ladybug 0.19 DROP INDEX leaves `_0_Leaf_vec_UPPER` / `0_id_docs` in catalog so
CREATE fails while SHOW_INDEXES omits the index; create_fts_and_vector used to
swallow that. Never drop FTS/VECTOR; ensure_indexes after upserts; rebuild =
delete kb.lbug. Add compose.edelweiss.yml + regression tests.

Co-authored-by: Cursor <cursoragent@cursor.com>

bin/kb/index

@@ -22,7 +22,7 @@ ROOT = Path(__file__).resolve().parents[2]
 sys.path.insert(0, str(ROOT / "bin" / "tools"))
 
 from kblib import (  # noqa: E402
-    connect, create_fts_and_vector, init_schema, upsert_leaf,
+    connect, ensure_indexes, init_schema, upsert_leaf,
     open_readonly, stats,
 )
 from mdleaves import read_markdown, to_all, walk_markdown  # noqa: E402
@@ -116,13 +116,11 @@ def main(argv: list[str]) -> int:
     db, conn = connect(DB_PATH, read_only=False)
     init_schema(conn)
 
-    # Keep the FTS/VECTOR indexes in place across incremental runs: ladybug's
-    # DROP INDEX leaves the backing tables registered on migrated DBs, so a
-    # drop+recreate silently kills the vector index. Only create when missing.
+    # Never DROP FTS/VECTOR (ghost catalog). Write leafs, then ensure indexes.
+    # --rebuild already deleted kb.lbug above, so CREATE runs on a clean DB.
     embed = embedder()
     done, total = index_leafs(conn, leafs, embed, a.limit)
-    if a.rebuild or not _has_indexes(conn):
-        create_fts_and_vector(conn, force=True)
+    ensure_indexes(conn)
     s = stats(conn)
     conn.close()
     db.close()
@@ -132,14 +130,5 @@ def main(argv: list[str]) -> int:
     return 0
 
 
-def _has_indexes(conn) -> bool:
-    try:
-        rows = conn.execute("CALL SHOW_INDEXES() RETURN *").get_all()
-        names = {row[1] for row in rows if row[0] == "Leaf"}
-        return "id" in names and "Leaf_vec" in names
-    except Exception:
-        return False
-
-
 if __name__ == "__main__":
     sys.exit(main(sys.argv[1:]))