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/domain/src/events/mod.rs

@@ -1,5 +1,5 @@
 use crate::entities::{DataSourceId, LayoutPresetId, WidgetId};
-use crate::value_objects::Layout;
+use crate::value_objects::{Layout, ThemeConfig};
 
 #[derive(Debug, Clone)]
 pub enum DomainEvent {
@@ -10,6 +10,7 @@ pub enum DomainEvent {
     DataSourceUpdated { id: DataSourceId },
     DataSourceRemoved { id: DataSourceId },
     LayoutChanged { layout: Layout },
+    ThemeChanged { theme: ThemeConfig },
     LayoutPresetSaved { id: LayoutPresetId },
     LayoutPresetLoaded { id: LayoutPresetId },
     LayoutPresetDeleted { id: LayoutPresetId },

crates/domain/src/lib.rs

@@ -16,6 +16,6 @@ pub use ports::{
 };
 pub use value_objects::{
     AlignItems, ContainerNode, Direction, DisplayHint, DisplayHintKind, HAlign, JustifyContent,
-    KeyMapping, Layout, LayoutChild, LayoutNode, LayoutValidationError, Sizing, VAlign, Value,
-    WidgetError, WidgetState,
+    KeyMapping, Layout, LayoutChild, LayoutNode, LayoutValidationError, Sizing, ThemeColor,
+    ThemeConfig, VAlign, Value, WidgetError, WidgetState,
 };

crates/domain/src/ports/broadcast.rs

@@ -1,5 +1,5 @@
 use crate::entities::WidgetId;
-use crate::value_objects::{DisplayHint, Layout, WidgetState};
+use crate::value_objects::{DisplayHint, Layout, ThemeConfig, WidgetState};
 use std::future::Future;
 
 pub trait BroadcastPort {
@@ -15,4 +15,9 @@ pub trait BroadcastPort {
         &self,
         updates: &[(WidgetId, DisplayHint, WidgetState)],
     ) -> impl Future<Output = Result<(), Self::Error>> + Send;
+
+    fn push_theme_update(
+        &self,
+        theme: &ThemeConfig,
+    ) -> impl Future<Output = Result<(), Self::Error>> + Send;
 }

crates/domain/src/ports/config_repository.rs

@@ -1,7 +1,7 @@
 use crate::entities::{
     DataSource, DataSourceId, LayoutPreset, LayoutPresetId, User, WidgetConfig, WidgetId,
 };
-use crate::value_objects::Layout;
+use crate::value_objects::{Layout, ThemeConfig};
 use std::future::Future;
 
 pub trait ConfigRepository {
@@ -51,6 +51,12 @@ pub trait ConfigRepository {
         id: LayoutPresetId,
     ) -> impl Future<Output = Result<(), Self::Error>> + Send;
 
+    fn get_theme(&self) -> impl Future<Output = Result<Option<ThemeConfig>, Self::Error>> + Send;
+    fn save_theme(
+        &self,
+        theme: &ThemeConfig,
+    ) -> impl Future<Output = Result<(), Self::Error>> + Send;
+
     fn get_user_by_username(
         &self,
         username: &str,

crates/domain/src/value_objects/mod.rs

@@ -1,5 +1,6 @@
 mod key_mapping;
 mod layout;
+mod theme;
 mod value;
 mod widget_state;
 
@@ -8,5 +9,6 @@ pub use layout::{
     AlignItems, ContainerNode, Direction, JustifyContent, Layout, LayoutChild, LayoutNode,
     LayoutValidationError, Sizing,
 };
+pub use theme::{ThemeColor, ThemeConfig};
 pub use value::Value;
 pub use widget_state::{DisplayHint, DisplayHintKind, HAlign, VAlign, WidgetError, WidgetState};

crates/domain/src/value_objects/theme.rs

@@ -0,0 +1,47 @@
+#[derive(Debug, Clone, PartialEq)]
+pub struct ThemeColor {
+    pub r: u8,
+    pub g: u8,
+    pub b: u8,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct ThemeConfig {
+    pub primary: ThemeColor,
+    pub secondary: ThemeColor,
+    pub accent: ThemeColor,
+    pub text: ThemeColor,
+    pub background: ThemeColor,
+}
+
+impl Default for ThemeConfig {
+    fn default() -> Self {
+        Self {
+            primary: ThemeColor {
+                r: 0x00,
+                g: 0x7A,
+                b: 0xCC,
+            },
+            secondary: ThemeColor {
+                r: 0x88,
+                g: 0x88,
+                b: 0x88,
+            },
+            accent: ThemeColor {
+                r: 0xE9,
+                g: 0x45,
+                b: 0x60,
+            },
+            text: ThemeColor {
+                r: 0xFF,
+                g: 0xFF,
+                b: 0xFF,
+            },
+            background: ThemeColor {
+                r: 0x00,
+                g: 0x00,
+                b: 0x00,
+            },
+        }
+    }
+}