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/adapters/http-api/src/routes/mod.rs

@@ -3,6 +3,7 @@ mod clients;
 mod data_sources;
 mod layout;
 mod presets;
+mod theme;
 mod webhook;
 mod widgets;
 
@@ -70,6 +71,11 @@ where
             get(layout::get_layout::<C, E, W, B, R, A, H>)
                 .put(layout::update_layout::<C, E, W, B, R, A, H>),
         )
+        .route(
+            "/theme",
+            get(theme::get_theme::<C, E, W, B, R, A, H>)
+                .put(theme::update_theme::<C, E, W, B, R, A, H>),
+        )
         .route(
             "/presets",
             get(presets::list_presets::<C, E, W, B, R, A, H>)

crates/adapters/http-api/src/routes/theme.rs

@@ -0,0 +1,46 @@
+use crate::AppState;
+use crate::extractors::AuthUser;
+use api_types::ThemeDto;
+use application::ConfigService;
+use axum::{extract::State, http::StatusCode, response::Json};
+use domain::{ConfigRepository, EventPublisher};
+
+type S<C, E, W, B, R, A, H> = State<AppState<C, E, W, B, R, A, H>>;
+
+pub async fn get_theme<C, E, W, B, R, A, H>(
+    _auth: AuthUser,
+    State(state): S<C, E, W, B, R, A, H>,
+) -> Result<Json<ThemeDto>, StatusCode>
+where
+    C: ConfigRepository,
+    C::Error: std::fmt::Debug,
+    E: EventPublisher,
+    E::Error: std::fmt::Debug,
+{
+    let theme = state
+        .config
+        .get_theme()
+        .await
+        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?
+        .unwrap_or_default();
+    Ok(Json(ThemeDto::from(&theme)))
+}
+
+pub async fn update_theme<C, E, W, B, R, A, H>(
+    _auth: AuthUser,
+    State(state): S<C, E, W, B, R, A, H>,
+    Json(body): Json<ThemeDto>,
+) -> Result<StatusCode, (StatusCode, String)>
+where
+    C: ConfigRepository,
+    C::Error: std::fmt::Debug,
+    E: EventPublisher,
+    E::Error: std::fmt::Debug,
+{
+    let theme = body.into_domain();
+    let svc = ConfigService::new(state.config.as_ref(), state.events.as_ref());
+    svc.update_theme(theme)
+        .await
+        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("{e}")))?;
+    Ok(StatusCode::OK)
+}