Preserve wrap state across change-preview-window

toggle-preview-wrap (and -wrap-word) modifies t.activePreviewOpts.wrap,
but change-preview-window resets t.previewOpts to t.initialPreviewOpts,
discarding the user's toggle. Carry wrap and wrapWord over so toggles
survive a layout change. Explicit wrap / nowrap tokens in the new spec
still win, so cycling and the empty-token reset are unaffected.

Close #4791

test/test_preview.rb

@@ -383,6 +383,49 @@ class TestPreview < TestInteractive
     end
   end
 
+  def test_change_preview_window_preserves_wrap_toggle
+    # https://github.com/junegunn/fzf/issues/4791
+    tmux.send_keys "#{FZF} --preview 'for i in $(seq $FZF_PREVIEW_COLUMNS); do echo -n .; done; echo -n .; echo wrapped; echo 2nd line' " \
+                   "--preview-window 'right,nowrap,border-rounded' " \
+                   '--bind ctrl-w:toggle-preview-wrap ' \
+                   '--bind ctrl-r:change-preview-window:border-bold', :Enter
+    sleep 2
+    # Initial: nowrap, rounded border. The long line is truncated; "wrapped" is hidden.
+    tmux.until do |lines|
+      assert_includes lines[2], '2nd line'
+      assert(lines.any? { it.include?('╭') })
+    end
+    # Toggle wrap on.
+    tmux.send_keys 'C-w'
+    tmux.until do |lines|
+      assert_includes lines[2], 'wrapped'
+      assert_includes lines[3], '2nd line'
+    end
+    # change-preview-window swaps the border to bold; wrap state must persist.
+    tmux.send_keys 'C-r'
+    tmux.until do |lines|
+      assert(lines.any? { it.include?('┏') })  # border actually changed
+      refute(lines.any? { it.include?('╭') })
+      assert_includes lines[2], 'wrapped'      # wrap was preserved
+      assert_includes lines[3], '2nd line'
+    end
+  end
+
+  def test_change_preview_window_overrides_wrap_explicitly
+    # When the new spec sets wrap/nowrap explicitly, it should still win.
+    tmux.send_keys "#{FZF} --preview 'for i in $(seq $FZF_PREVIEW_COLUMNS); do echo -n .; done; echo -n .; echo wrapped; echo 2nd line' " \
+                   "--preview-window 'right,wrap' " \
+                   '--bind ctrl-r:change-preview-window:nowrap', :Enter
+    # Initial: wrap is on.
+    tmux.until do |lines|
+      assert_includes lines[2], 'wrapped'
+      assert_includes lines[3], '2nd line'
+    end
+    # Explicit nowrap in the spec must override the (initially wrapped) state.
+    tmux.send_keys 'C-r'
+    tmux.until { |lines| assert_includes lines[2], '2nd line' }
+  end
+
   def test_preview_follow_wrap
     tmux.send_keys "seq 1 | #{FZF} --preview 'seq 1000' --preview-window right,2,follow,wrap", :Enter
     tmux.until { |lines| assert_equal 1, lines.match_count }