Prep for AngularFire v21

[jamesdaniels]

• Bump all Angular dependencies to ^21.0.0 build to ~0.2100.0
• Bump firebase to next major
• Drop vertexai
• Lots of lint and tsconfig drama
• Unbork Github Actions

[aleDellaJanna]

Any news about angular 21 support?

[byrondover]

Hey @jamesdaniels — just wanted to say thanks for all the hard work you've put into AngularFire over the years. It’s been a huge part of my workflow for almost 10 years now, and I really appreciate the care you put into keeping it alive and excellent.

Stoked for the release of v21! Grateful for everything you do, it's appreciated more than you probably hear. Thank you for making the Angular + Firebase experience so good.

🙏

[jamesdaniels]

@byrondover appreciate that, thank you :) Wish I had more time to dedicate, maybe I'll find some time after the new year to do something fun with signals.