components: add CollapsingScaffold + OptionPicker/FullScreenPicker (batch-2)

The family's collapsing settings/sub-screen scaffold and the full-screen
single-select picker built on it (used for theme/list/reminder option dialogs).
Adds material-icons-core (ArrowBack/Check) and a generic 'back' string apps can
override. ReminderFormatting (labels over app-specific R.plurals + per-app
presets) deliberately NOT included — it needs a label-callback API, a separate
pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

components/build.gradle.kts

@@ -37,4 +37,5 @@ dependencies {
     implementation(libs.androidx.ui)
     implementation(libs.androidx.foundation)
     implementation(libs.androidx.material3)
+    implementation(libs.androidx.material.icons.core)
 }