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/Code/CodeButtons/CodeRunButton.vue

@@ -40,7 +40,7 @@ export default defineComponent({
 function getCanRunState(
   selectedOs: OperatingSystem,
   isDesktopVersion: boolean,
-  hostOs: OperatingSystem,
+  hostOs: OperatingSystem | undefined,
 ): boolean {
   const isRunningOnSelectedOs = selectedOs === hostOs;
   return isDesktopVersion && isRunningOnSelectedOs;