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)
 }

components/src/main/kotlin/de/jeanlucmakiola/floret/components/CollapsingScaffold.kt

@@ -0,0 +1,83 @@
+package de.jeanlucmakiola.floret.components
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.ColumnScope
+import androidx.compose.foundation.layout.consumeWindowInsets
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.imePadding
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.rounded.ArrowBack
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.LargeTopAppBar
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.material3.rememberTopAppBarState
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.input.nestedscroll.nestedScroll
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+
+/**
+ * The family's collapsing scaffold for settings hubs, sub-screens and the
+ * full-screen pickers: a [LargeTopAppBar] that collapses on scroll, a back
+ * button, and a vertically scrolling content column. [content] lays out the
+ * connected grouped rows. The back content description uses the kit's `back`
+ * string, which an app can override with its own (localized) `back`.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun CollapsingScaffold(
+    title: String,
+    onBack: () -> Unit,
+    modifier: Modifier = Modifier,
+    content: @Composable ColumnScope.() -> Unit,
+) {
+    val scrollBehavior =
+        TopAppBarDefaults.exitUntilCollapsedScrollBehavior(rememberTopAppBarState())
+    Scaffold(
+        modifier = modifier
+            .fillMaxSize()
+            .background(MaterialTheme.colorScheme.surface)
+            .nestedScroll(scrollBehavior.nestedScrollConnection),
+        topBar = {
+            LargeTopAppBar(
+                title = { Text(title) },
+                navigationIcon = {
+                    IconButton(onClick = onBack) {
+                        Icon(
+                            Icons.AutoMirrored.Rounded.ArrowBack,
+                            contentDescription = stringResource(R.string.back),
+                        )
+                    }
+                },
+                scrollBehavior = scrollBehavior,
+                colors = TopAppBarDefaults.largeTopAppBarColors(
+                    scrolledContainerColor = MaterialTheme.colorScheme.surface,
+                ),
+            )
+        },
+    ) { innerPadding ->
+        Column(
+            modifier = Modifier
+                .padding(innerPadding)
+                // Consume the scaffold's bar insets so imePadding adds only the
+                // keyboard height beyond them (max, not sum).
+                .consumeWindowInsets(innerPadding)
+                .fillMaxSize()
+                .background(MaterialTheme.colorScheme.surface)
+                .imePadding()
+                .verticalScroll(rememberScrollState())
+                .padding(top = 8.dp, bottom = 24.dp),
+            content = content,
+        )
+    }
+}

components/src/main/kotlin/de/jeanlucmakiola/floret/components/OptionPicker.kt

@@ -0,0 +1,79 @@
+package de.jeanlucmakiola.floret.components
+
+import androidx.compose.foundation.layout.ColumnScope
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.rounded.Check
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.window.Dialog
+import androidx.compose.ui.window.DialogProperties
+
+/**
+ * Full-screen scaffold for selection pickers: a full-bleed [Dialog] that reuses
+ * [CollapsingScaffold] (collapsing title + back), so a picker is visually
+ * identical to a settings sub-page and uses the full width. [content] places the
+ * connected grouped rows; selecting one calls [onDismiss].
+ */
+@Composable
+fun FullScreenPicker(
+    title: String,
+    onDismiss: () -> Unit,
+    content: @Composable ColumnScope.() -> Unit,
+) {
+    Dialog(
+        onDismissRequest = onDismiss,
+        properties = DialogProperties(
+            usePlatformDefaultWidth = false,
+            decorFitsSystemWindows = false,
+        ),
+    ) {
+        CollapsingScaffold(title = title, onBack = onDismiss, content = content)
+    }
+}
+
+/**
+ * General single-select picker, full-screen: each option is a connected grouped
+ * row and the current one carries a check. The drop-in for the family's option
+ * dialogs (theme, default list, reminder offset, …).
+ */
+@Composable
+fun <T> OptionPicker(
+    title: String,
+    options: List<T>,
+    selected: T,
+    label: @Composable (T) -> String,
+    onSelect: (T) -> Unit,
+    onDismiss: () -> Unit,
+    leading: (@Composable (T) -> Unit)? = null,
+) {
+    FullScreenPicker(title = title, onDismiss = onDismiss) {
+        options.forEachIndexed { index, option ->
+            val isSelected = option == selected
+            GroupedRow(
+                title = label(option),
+                position = positionOf(index, options.size),
+                selected = isSelected,
+                leading = leading?.let { { it(option) } },
+                trailing = if (isSelected) {
+                    { SelectedCheck() }
+                } else {
+                    null
+                },
+                onClick = {
+                    onSelect(option)
+                    onDismiss()
+                },
+            )
+        }
+    }
+}
+
+@Composable
+private fun SelectedCheck() {
+    Icon(
+        imageVector = Icons.Rounded.Check,
+        contentDescription = null,
+        tint = MaterialTheme.colorScheme.primary,
+    )
+}

components/src/main/res/values/strings.xml

@@ -0,0 +1,7 @@
+<resources>
+    <!--
+      Generic component strings. App-agnostic fallbacks; an app may override any
+      of these with its own (localized) value via resource merge.
+    -->
+    <string name="back">Back</string>
+</resources>

gradle/libs.versions.toml

@@ -17,6 +17,7 @@ androidx-compose-bom = { group = "androidx.compose", name = "compose-bom", versi
 androidx-ui = { group = "androidx.compose.ui", name = "ui" }
 androidx-foundation = { group = "androidx.compose.foundation", name = "foundation" }
 androidx-material3 = { group = "androidx.compose.material3", name = "material3", version.ref = "material3" }
+androidx-material-icons-core = { group = "androidx.compose.material", name = "material-icons-core" }
 
 junit-jupiter-api = { group = "org.junit.jupiter", name = "junit-jupiter-api", version.ref = "junit" }
 junit-jupiter-engine = { group = "org.junit.jupiter", name = "junit-jupiter-engine", version.ref = "junit" }