Seed the range-set-integration branch with a handoff plan summarizing the
current range_predicate / seq_range_collapse infrastructure in master, the
two candidate integration approaches (first-class re.ranges AST node vs.
deeper internal-only use of range-sets), and a concrete evaluation plan
against master on the regex-equivalence and QF_S benchmarks.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
