refactor: migrate from Angular v15 to v16

* Perform auto-migrations from `ng update`
  * Remove `CanActivate` interface implementations
* Bump CI Node.js versions from v14.x to v18.x

Author: EdricChan03

.github/workflows/main.yml

@@ -15,7 +15,7 @@ jobs:
     - name: Setup NodeJS LTS
       uses: actions/setup-node@v6
       with:
-        node-version: '14.x'
+        node-version: '18.x'
     - name: Setup Angular problem matchers
       uses: EdricChan03/angular-problem-matchers-action@v0.0.0
     - name: Cache node modules

.github/workflows/pull-request.yml

@@ -15,7 +15,7 @@ jobs:
     - name: Setup NodeJS LTS
       uses: actions/setup-node@v6
       with:
-        node-version: '14.x'
+        node-version: '18.x'
     - name: Cache node modules
       uses: actions/cache@v5
       id: node_modules_cache