Migrating findViewById to ViewBinding

Instructions

findViewById returns View (pre-API 26 it was unchecked) and relies on string-like IDs resolved at runtime. Every rename, deletion, or typo becomes an NPE or ClassCastException. ViewBinding replaces this with a generated, null-safe class per layout.

1. Enable ViewBinding

app/build.gradle:

android {
    buildFeatures {
        viewBinding true
    }
}

Do not enable DataBinding yet — it has a different migration surface and a heavier annotation processor.