Unit count (#1402)

## Description:

Use an iterative approach to counting units to reduce array allocations.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [ ] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

src/client/index.html

@@ -187,7 +187,7 @@
           <territory-patterns-modal class="w-[20%] md:w-[15%]">
             <button
               id="territory-patterns-input-preview-button"
-              class="w-full border p-[4px] rounded-lg flex cursor-pointer border-black/30 dark:border-gray-300/60 bg-white/70 dark:bg-[rgba(55,65,81,0.7)]"
+              class="w-full border p-[4px] rounded-lg flex cursor-pointer border-black/30 dark:border-gray-300/60 bg-white/70 dark:bg-[rgba(55,65,81,0.7)] justify-center"
               title="Pick a pattern!"
             ></button>
           </territory-patterns-modal>