[ESLint 9/10] sonarjs complexity

[ShaileshParmar11]

Part of epic #30977.

cyclomatic/cognitive/expression complexity + nested-conditional/nested-functions. ~60 safe refactors; rest disable-with-reason. 899 warnings.

Delivered as PR 7 of 10 (stacked). Behavior-preserving; verified via ESLint before/after + tsc regression check.