feat(android): safe-area insets for HUD positioning

Adds SafeAreaInsets resource + SafeAreaInsetsPlugin that report the
OS-reserved regions (status bar, gesture/nav bar, display cutout)
around the playable surface. Desktop reports all zeros; Android
queries WindowInsets.getInsets(systemBars()) via JNI on the decor
view, polling for up to 120 frames since getRootWindowInsets()
returns null until the view is laid out.

UI that should respect the top inset carries a SafeAreaAnchoredTop
{ base_top } marker. A change-detection system re-applies
`base_top + insets.top` whenever the resource changes, so late
inset arrival (frame 1-3 on Android) and future orientation
changes flow through without re-spawning entities.

Wires the three top-anchored HUD spawn sites — hud_band, hud
column, action button row — to the new pattern. Spawn systems
take Option<Res<SafeAreaInsets>> so HudPlugin still works
standalone in unit tests (mirrors the existing FontResource
pattern).

Closes P0 #1 of docs/android/PLAYABILITY_TODO.md. Resolves the
status-bar/HUD collision visible in the v0.22.3 hardware
screenshot.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_engine/src/hud_plugin.rs

@@ -17,6 +17,8 @@ use crate::daily_challenge_plugin::DailyChallengeResource;
 use crate::progress_plugin::ProgressResource;
 use crate::settings_plugin::SettingsResource;
 use crate::layout::HUD_BAND_HEIGHT;
+use crate::safe_area::{SafeAreaAnchoredTop, SafeAreaInsets};
+use crate::ui_theme::SPACE_2;
 use crate::ui_theme::{
     scaled_duration, ACCENT_PRIMARY, ACCENT_SECONDARY, BG_ELEVATED, BG_ELEVATED_HI,
     BG_ELEVATED_PRESSED, BG_HUD_BAND, BORDER_SUBTLE, HighContrastBorder, MOTION_SCORE_PULSE_SECS,
@@ -376,11 +378,13 @@ impl Plugin for HudPlugin {
 /// bottom edge lines up exactly with the top edge of the highest
 /// playable card. The fill is `BG_HUD_BAND` — midnight purple at 0.70
 /// alpha, so the green felt reads through subtly.
-fn spawn_hud_band(mut commands: Commands) {
+fn spawn_hud_band(insets: Option<Res<SafeAreaInsets>>, mut commands: Commands) {
+    const BASE_TOP: f32 = 0.0;
+    let top_inset = insets.as_deref().copied().unwrap_or_default().top;
     commands.spawn((
         Node {
             position_type: PositionType::Absolute,
-            top: Val::Px(0.0),
+            top: Val::Px(BASE_TOP + top_inset),
             left: Val::Px(0.0),
             width: Val::Percent(100.0),
             height: Val::Px(HUD_BAND_HEIGHT),
@@ -391,6 +395,7 @@ fn spawn_hud_band(mut commands: Commands) {
         // paint on top, but above the card sprites (which are 2D-world
         // entities and rendered behind UI regardless).
         ZIndex(Z_HUD - 1),
+        SafeAreaAnchoredTop { base_top: BASE_TOP },
     ));
 }
 
@@ -413,7 +418,12 @@ fn spawn_hud_band(mut commands: Commands) {
 /// player's #1 complaint. This restructure groups by purpose, lets
 /// transient items disappear cleanly, and uses the typography scale to
 /// make Score the visual protagonist.
-fn spawn_hud(font_res: Option<Res<FontResource>>, mut commands: Commands) {
+fn spawn_hud(
+    font_res: Option<Res<FontResource>>,
+    insets: Option<Res<SafeAreaInsets>>,
+    mut commands: Commands,
+) {
+    let top_inset = insets.as_deref().copied().unwrap_or_default().top;
     let font_handle = font_res.as_ref().map(|f| f.0.clone()).unwrap_or_default();
     let font_score = TextFont {
         font: font_handle.clone(),
@@ -443,12 +453,13 @@ fn spawn_hud(font_res: Option<Res<FontResource>>, mut commands: Commands) {
             Node {
                 position_type: PositionType::Absolute,
                 left: VAL_SPACE_3,
-                top: VAL_SPACE_2,
+                top: Val::Px(SPACE_2 + top_inset),
                 flex_direction: FlexDirection::Column,
                 row_gap: VAL_SPACE_1,
                 ..default()
             },
             ZIndex(Z_HUD),
+            SafeAreaAnchoredTop { base_top: SPACE_2 },
         ))
         .with_children(|hud| {
             // Tier 1 — primary readouts. Score is the protagonist (HEADLINE);
@@ -568,7 +579,12 @@ fn spawn_hud(font_res: Option<Res<FontResource>>, mut commands: Commands) {
 /// Order (left → right): Undo, Pause, Help, New Game. New Game is rightmost
 /// because it's the most consequential action; the destructive button sits
 /// on its own visual edge.
-fn spawn_action_buttons(font_res: Option<Res<FontResource>>, mut commands: Commands) {
+fn spawn_action_buttons(
+    font_res: Option<Res<FontResource>>,
+    insets: Option<Res<SafeAreaInsets>>,
+    mut commands: Commands,
+) {
+    let top_inset = insets.as_deref().copied().unwrap_or_default().top;
     let font = TextFont {
         font: font_res.as_ref().map(|f| f.0.clone()).unwrap_or_default(),
         // TYPE_BODY (14.0) — was a hardcoded `16.0` until the
@@ -585,13 +601,14 @@ fn spawn_action_buttons(font_res: Option<Res<FontResource>>, mut commands: Comma
             Node {
                 position_type: PositionType::Absolute,
                 right: VAL_SPACE_3,
-                top: VAL_SPACE_2,
+                top: Val::Px(SPACE_2 + top_inset),
                 flex_direction: FlexDirection::Row,
                 column_gap: VAL_SPACE_2,
                 align_items: AlignItems::Center,
                 ..default()
             },
             ZIndex(Z_HUD),
+            SafeAreaAnchoredTop { base_top: SPACE_2 },
         ))
         .with_children(|row| {
             // Menu and Modes don't have a single hotkey accelerator