Consolidate 141 BDD feature files that each complete in under 0.1 seconds
into 25 domain-grouped feature files, reducing subprocess count from 339
to ~223. Each consolidated file groups scenarios from the same domain/module
that share step definitions and fixtures. All scenarios are preserved with
clear comment headers indicating their original source file.
This reduces subprocess overhead by ~116 invocations (141 original files
replaced by 25 consolidated files), targeting the 42% of subprocess count
that contributed only 0.2% of actual test runtime.
ISSUES CLOSED: #485
