fix(neo4j): splitStatements only splits on RETURN

[hemanta212]

Fix: splitStatements only splits on RETURN

isComplete() was too aggressive - treated any write keyword (CREATE/MERGE/DELETE) as "complete", causing premature splits that broke variable bindings in chained CREATE clauses.

Bug case

MATCH (alice:User {id: 1}), (bob:User {id: 2})
CREATE (c1:Comment {id: 1, text: "Great post!"})
CREATE (bob)-[:WROTE]->(c1)

Was split into 3 statements - bob and c1 became undefined in subsequent statements, creating orphan nodes.

Change

// Before: split on any write keyword
isComplete := func(s string) bool {
    if strings.Contains(upper, "RETURN") { return true }
    for _, kw := range writeKeywords { // CREATE, MERGE, DELETE...
        if strings.Contains(upper, kw) { return true }
    }
    return false
}

// After: only split on RETURN
isComplete := func(s string) bool {
    return strings.Contains(upper, "RETURN ") || strings.HasSuffix(upper, "RETURN")
}

Starter keywords unchanged (MATCH, CREATE, MERGE, DETACH, OPTIONAL, CALL, UNWIND, FOREACH).

Result

• MATCH...CREATE...CREATE stays together (no RETURN)
• ...RETURN x then CREATE/MATCH... splits correctly
• crud example: 58/58 passing

[rlch]

Add tests