theme config, layout preview, container alignment

Server: ThemeConfig entity + CRUD (GET/PUT /theme), SQLite persistence,
ThemeUpdate broadcast to ESP32 on save and initial connect.
Client: render engine uses theme colors, full-screen redraw on theme change.
SPA: theme page with color pickers + presets, layout preview with TS port
of layout engine, justify/align controls on containers.
DisplayHint refactored to struct (kind + h_align + v_align).

crates/application/tests/config_service_tests.rs

@@ -3,8 +3,8 @@ mod support;
 use application::ConfigService;
 use domain::{
     AlignItems, ConfigRepository, ContainerNode, DataSource, DataSourceConfig, DataSourceType,
-    Direction, DisplayHint, DisplayHintKind, DomainEvent, JustifyContent, KeyMapping, Layout, LayoutChild,
-    LayoutNode, LayoutPreset, Sizing, WidgetConfig,
+    Direction, DisplayHint, DisplayHintKind, DomainEvent, JustifyContent, KeyMapping, Layout,
+    LayoutChild, LayoutNode, LayoutPreset, Sizing, WidgetConfig,
 };
 use std::time::Duration;
 use support::{InMemoryConfigRepository, InMemoryEventPublisher};

crates/application/tests/support/mod.rs

@@ -1,6 +1,6 @@
 use domain::{
     ConfigRepository, DataSource, DataSourceId, DomainEvent, EventPublisher, Layout, LayoutPreset,
-    LayoutPresetId, User, WidgetConfig, WidgetId,
+    LayoutPresetId, ThemeConfig, User, WidgetConfig, WidgetId,
 };
 use std::collections::HashMap;
 use std::sync::Mutex;
@@ -9,6 +9,7 @@ pub struct InMemoryConfigRepository {
     widgets: Mutex<HashMap<WidgetId, WidgetConfig>>,
     data_sources: Mutex<HashMap<DataSourceId, DataSource>>,
     layout: Mutex<Option<Layout>>,
+    theme: Mutex<Option<ThemeConfig>>,
     presets: Mutex<HashMap<LayoutPresetId, LayoutPreset>>,
 }
 
@@ -18,6 +19,7 @@ impl InMemoryConfigRepository {
             widgets: Mutex::new(HashMap::new()),
             data_sources: Mutex::new(HashMap::new()),
             layout: Mutex::new(None),
+            theme: Mutex::new(None),
             presets: Mutex::new(HashMap::new()),
         }
     }
@@ -92,6 +94,15 @@ impl ConfigRepository for InMemoryConfigRepository {
         Ok(())
     }
 
+    async fn get_theme(&self) -> Result<Option<ThemeConfig>, Self::Error> {
+        Ok(self.theme.lock().unwrap().clone())
+    }
+
+    async fn save_theme(&self, theme: &ThemeConfig) -> Result<(), Self::Error> {
+        *self.theme.lock().unwrap() = Some(theme.clone());
+        Ok(())
+    }
+
     async fn get_preset(&self, id: LayoutPresetId) -> Result<Option<LayoutPreset>, Self::Error> {
         Ok(self.presets.lock().unwrap().get(&id).cloned())
     }