chore: remove unused Angular Material/CDK before v22 upgrade

Material and CDK were installed but no component from either package
was used in any template - only the indigo-pink.css prebuilt theme was
loaded. Removing them shrinks the surface area for the upcoming
Angular 17 to 22 migration.

Also fixes app.component.spec.ts, which asserted on a `title` property
and an `<h1>` that no longer exist on AppComponent (stale CLI
boilerplate), so `ng test` can be used as a gate at each migration step.

Author: samuelsonbrito

angular.json

@@ -20,7 +20,6 @@
             "tsConfig": "tsconfig.app.json",
             "assets": ["src/favicon.ico", "src/assets"],
             "styles": [
-              "@angular/material/prebuilt-themes/indigo-pink.css",
               "src/styles.css"
             ],
             "scripts": [
@@ -75,7 +74,6 @@
             "tsConfig": "tsconfig.spec.json",
             "assets": ["src/favicon.ico", "src/assets"],
             "styles": [
-              "@angular/material/prebuilt-themes/indigo-pink.css",
               "src/styles.css"
             ],
             "scripts": [