feat: Add conditional question support with `when` clause in brick.yaml

## **Hey there! 👋** So I've been working with mason bricks and noticed something that could really improve the user experience. Right now, when you create a brick with multiple options (like different auth methods), users get bombarded with irrelevant questions. ## **The Problem** Imagine this scenario - you're creating a Flutter app and you select "no_auth" as your authentication method, but then mason still asks you: - "Do you want to enable Google Sign-In with Firebase?" - "Do you want to enable Apple Sign-In with Firebase?" Like... what? 😅 That doesn't make any sense! If I chose no auth, why am I getting Firebase questions? ## **What I'm Proposing** Add a simple `when` clause to brick.yaml variables so we can conditionally show questions based on previous answers. Something like this: ```yaml vars: auth_method: type: enum values: [firebase, custom_jwt, no_auth] default: firebase prompt: Which authentication method do you want to use? firebase_google: type: boolean default: true prompt: Do you want to enable Google Sign-In with Firebase? when: auth_method == firebase # Only show if firebase is selected firebase_apple: type: boolean default: true prompt: Do you want to enable Apple Sign-In with Firebase? when: auth_method == firebase # Only show if firebase is selected ``` ## **Why This Matters** **Current Flow (Confusing):** ? Which authentication method do you want to use? no_auth ? Do you want to enable Google Sign-In with Firebase? (Y/n) 🤔 ? Do you want to enable Apple Sign-In with Firebase? (Y/n) �� * **With `when` clause (Clean):** ## **What Needs to Be Done** ### **Parser Stuff:** - [ ] Make brick.yaml understand `when` conditions - [ ] Add validation for condition syntax - [ ] Support basic operators like `==`, `!=`, `in`, `not in` ## **Real-World Example** I'm building a Flutter Riverpod starter brick, and when someone selects "no_auth", they still get Firebase questions. It's super confusing! This feature would fix that instantly. --- **TL;DR:** Add `when` clauses to brick.yaml so questions only show when they're relevant. Makes mason way more user-friendly! 🚀