Refactor to enforce strictNullChecks

This commit applies `strictNullChecks` to the entire codebase to improve
maintainability and type safety. Key changes include:

- Remove some explicit null-checks where unnecessary.
- Add necessary null-checks.
- Refactor static factory functions for a more functional approach.
- Improve some test names and contexts for better debugging.
- Add unit tests for any additional logic introduced.
- Refactor `createPositionFromRegexFullMatch` to its own function as the
  logic is reused.
- Prefer `find` prefix on functions that may return `undefined` and
  `get` prefix for those that always return a value.

src/presentation/components/Scripts/View/Cards/CardList.vue

@@ -10,7 +10,7 @@
       </div>
     -->
     <div
-      v-if="categoryIds != null && categoryIds.length > 0"
+      v-if="categoryIds.length > 0"
       class="cards"
     >
       <CardListItem
@@ -50,8 +50,9 @@ export default defineComponent({
     const { currentState, onStateChange } = injectKey((keys) => keys.useCollectionState);
 
     const width = ref<number>(0);
-    const categoryIds = computed<ReadonlyArray<number>>(() => currentState
-      .value.collection.actions.map((category) => category.id));
+    const categoryIds = computed<readonly number[]>(
+      () => currentState.value.collection.actions.map((category) => category.id),
+    );
     const activeCategoryId = ref<number | undefined>(undefined);
 
     function onSelected(categoryId: number, isExpanded: boolean) {

src/presentation/components/Scripts/View/Cards/CardListItem.vue

@@ -89,12 +89,9 @@ export default defineComponent({
 
     const cardElement = shallowRef<HTMLElement>();
 
-    const cardTitle = computed<string | undefined>(() => {
-      if (!props.categoryId || !currentState.value) {
-        return undefined;
-      }
-      const category = currentState.value.collection.findCategory(props.categoryId);
-      return category?.name;
+    const cardTitle = computed<string>(() => {
+      const category = currentState.value.collection.getCategory(props.categoryId);
+      return category.name;
     });
 
     function collapse() {
@@ -102,8 +99,12 @@ export default defineComponent({
     }
 
     async function scrollToCard() {
+      const card = cardElement.value;
+      if (!card) {
+        throw new Error('Card is not found');
+      }
       await sleep(400); // wait a bit to allow GUI to render the expanded card
-      cardElement.value.scrollIntoView({ behavior: 'smooth' });
+      card.scrollIntoView({ behavior: 'smooth' });
     }
 
     return {

src/presentation/components/Scripts/View/Cards/CardSelectionIndicator.vue

@@ -34,7 +34,7 @@ export default defineComponent({
     const currentCollection = computed<ICategoryCollection>(() => currentState.value.collection);
 
     const currentCategory = computed<ICategory>(
-      () => currentCollection.value.findCategory(props.categoryId),
+      () => currentCollection.value.getCategory(props.categoryId),
     );
 
     const isAnyChildSelected = computed<boolean>(