Port Go server/subject_transform.go to .NET. Implements a compiled
transform engine that parses source patterns with wildcards and
destination templates with function tokens at Create() time, then
evaluates them efficiently at Apply() time without runtime regex.
Supports all 9 transform functions: wildcard/$N, partition (FNV-1a),
split, splitFromLeft, splitFromRight, sliceFromLeft, sliceFromRight,
left, and right. Used for stream mirroring, account imports/exports,
and subject routing.
