Avoid needless word-list copies in Lorem.words (#3292)

Only concatenate the supplemental list when requested, and only
duplicate the word list when more words are asked for than the list
contains. The list returned by translate is never mutated, since it may
be the array cached by the I18n backend.

Benchmark (Ruby 3.4.9, arm64-darwin25, benchmark-ips):

    require 'benchmark/ips'
    require 'faker'

    Benchmark.ips do |x|
      x.config(warmup: 2, time: 5)
      x.report('words(number: 4)') { Faker::Lorem.words(number: 4) }
      x.report('sentence') { Faker::Lorem.sentence }
      x.report('paragraph') { Faker::Lorem.paragraph }
    end

Results:

    main:        words(number: 4)  126.489k (+/- 2.2%) i/s
                 sentence           40.797k (+/- 4.4%) i/s
                 paragraph          12.455k (+/- 0.7%) i/s
    this commit: words(number: 4)  132.863k (+/- 1.0%) i/s  (~1.05x)
                 sentence           43.273k (+/- 0.4%) i/s  (~1.06x)
                 paragraph          12.733k (+/- 1.4%) i/s  (~1.02x)

Author: connorshea

lib/faker/default/lorem.rb

@@ -36,15 +36,16 @@ def word(exclude_words: nil)
       # @faker.version 2.1.3
       def words(number: 3, supplemental: false, exclude_words: nil)
         resolved_num = resolve(number)
-        word_list = (
-          translate('faker.lorem.words') +
-          (supplemental ? translate('faker.lorem.supplemental') : [])
-        )
+        word_list = translate('faker.lorem.words')
+        word_list += translate('faker.lorem.supplemental') if supplemental
         if exclude_words
           exclude_words = exclude_words.split(', ') if exclude_words.instance_of?(::String)
           word_list -= exclude_words
         end
-        word_list *= ((resolved_num / word_list.length) + 1)
+        # Duplicate the word list only when more words are requested than the
+        # list contains. Never mutate word_list itself: it may be the array
+        # cached by the I18n backend.
+        word_list *= ((resolved_num / word_list.length) + 1) if resolved_num > word_list.length
         sample(word_list, resolved_num)
       end