Rename non-screaming-snake-case constants (ConstantName, 54 violations)

[sspaink]

ConstantName flags static final fields that don't match ^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$. 54 violations.

Where

• ~50 files in opa-evaluator/.../ir/stmts/*Stmt.java, each with private static final String StmtType = "..." — should be STMT_TYPE.
• A handful of test files with constants like objectMapper that should either lose static final (they're just helpers) or be renamed.

Fix

Mechanical. Each rename is local (constant is private), so this is one safe bulk PR. IDE refactor → rename handles all *Stmt.java cases.

Note: Stmt.java:10 is also flagged by TypeName for an interface field named STMT_TYPE — Checkstyle is misclassifying because of how it's declared. Leave that one to the long-tail mop-up issue.

[shanksmp]

Hi @sspaink, I’d like to work on this.

I’ll rename the private static final constants in the stmt classes, update local references, handle the test constants mentioned, and leave Stmt.java:10 unchanged as noted in the issue.