Replace the FPC/Delphi replace surface (ReplaceStr, ReplaceText, and the
proposed StringReplace + TReplaceFlags set) with two self-explanatory
functions:
Replace(S, Old, New) — replaces the FIRST occurrence
ReplaceAll(S, Old, New) — replaces EVERY occurrence
Both are case-sensitive and literal (non-pattern). This sheds the legacy
redundancy: ReplaceStr/ReplaceText were two names for one operation split by
a 'String vs Text' distinction that is not obvious, and Delphi's StringReplace
encodes the same two booleans (all-vs-first, sensitive-vs-insensitive) as an
awkward flag-set. Modern languages (Go, Python, Java, Rust) use a plain
first/all split with no case flag.
Case-insensitive replace is expressed by lower-casing the inputs with the
built-in LowerCase/UpperCase before calling Replace/ReplaceAll; a
case-*preserving* insensitive replace and pattern/regex matching are deferred
and recorded in docs/future-improvements.adoc.
The internal worker keeps the existing TStringBuilder-based loop; it gains a
FirstOnly flag and drops the now-unused case-fold path.
No callers of the removed functions existed anywhere in the tree. IR/semantic
and e2e tests updated to the new names; both fixpoints green (FIXPOINT_OK,
NATIVE_FIXPOINT_OK, NATIVE_INTERNAL_OK); full suite OK (3346 tests).
2f54707a63