ALL-2049: address CodeRabbit + Cursor findings on ALL-2017 filter-expression PR

Follow-up PR for merged #12881. 9 review findings across buildEsFromExpression, buildPrismaFromExpression, expressionEngine, filterExpression.test.ts, index.ts, types.ts, validateExpression.ts, subgraph/schema/queries/devices.ts. Branch artem-agent/ALL-2049-filter-expression-review-fixes off latest main. Linear ALL-2049.