Restore Range#overlap? for Ruby < 3.3 (guarded)

Ruby 3.3 added a native Range#overlap?, and Facets dropped its own version
in the 3.2 modernization -- which left 3.1/3.2 users without it. Bring the
method back under a `method_defined?(:overlap?)` guard so it backfills on
older Rubies without replacing the built-in on 3.3+. Wire it into range.rb
and add a test.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: trans

lib/core/facets/range.rb

@@ -1,4 +1,5 @@
 require_relative 'range/combine.rb'
+require_relative 'range/overlap.rb'
 #require_relative 'range/intersection.rb' # too new
 #require_relative 'range/quantile.rb'     # uncommon
 #require_relative 'range/op_add.rb'       # too new

lib/core/facets/range/overlap.rb

@@ -0,0 +1,19 @@
+class Range
+
+  # Do two ranges overlap?
+  #
+  #   (1..5).overlap?(3..8)   #=> true
+  #   (1..5).overlap?(6..8)   #=> false
+  #
+  # Ruby 3.3 added a native Range#overlap?, so only define Facets' version
+  # on older Rubies that lack it -- this avoids replacing the built-in.
+  #
+  # CREDIT: Daniel Schierbeck, Brandon Keepers
+
+  unless method_defined?(:overlap?)
+    def overlap?(other)
+      include?(other.first) or other.include?(first)
+    end
+  end
+
+end

test/core/range/test_overlap.rb

@@ -0,0 +1,25 @@
+covers 'facets/range/overlap'
+
+test_case Range do
+
+  method :overlap? do
+
+    test "true when two ranges share elements" do
+      (1..5).overlap?(3..8).assert == true
+    end
+
+    test "false when two ranges are disjoint" do
+      (1..5).overlap?(6..8).assert == false
+    end
+
+    test "true when ranges touch at a boundary" do
+      (1..5).overlap?(5..9).assert == true
+    end
+
+    test "true when one range contains the other" do
+      (1..10).overlap?(3..5).assert == true
+    end
+
+  end
+
+end