Add braces to single-line if/else (NeedBraces, 335 violations)

[sspaink]

NeedBraces flags if (cond) doThing(); patterns. 335 instances across ~80 files.

Top offenders

• opa-evaluator/.../mapper/ClassInfo.java — 10
• opa-evaluator/.../ir/stmts/{ObjectInsertStmt,WithStmt,ScanStmt}.java — 8 each
• opa-evaluator/.../mapper/RegoMapper.java — 8
• ~75 other files with 1–7 each

Fix

Mechanical. IDE auto-fix ("Add braces around statement") handles all of them. Safe to do in one PR or split per package.

Reproducing

```
./gradlew checkstyleMain checkstyleTest --continue
grep -r "NeedBraces" /build/reports/checkstyle/.xml
```