ng add silently exits with "Nothing to be done." if no features are selected #3716

Version info

Angular: 21.2.x Firebase: 12.x AngularFire: 21.0.0-rc.0

How to reproduce these conditions

1. Run ng add @angular/fire (or @angular/fire@next).
2. At the ? What features would you like to setup? prompt, press Enter without pressing Space on any option first.

Expected behavior

Either the schematic explains that no features were selected and that Space toggles a choice, or it otherwise makes clear that setup did not happen because of the empty selection.

Actual behavior

The Angular CLI prints its generic:

Nothing to be done.

with no indication that Space was needed to select a feature. ngAddSetupProject (src/schematics/setup/index.ts) gates its entire setup flow on features.length > 0; an empty selection from the checkbox prompt (default: []) skips that block and returns nothing, which is indistinguishable from "there was genuinely nothing to configure." A first-time user has no way to tell they made a mistake versus the tool having nothing to do.