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/config-sqlite/src/lib.rs

@@ -87,6 +87,15 @@ impl SqliteConfigStore {
         .execute(&self.pool)
         .await?;
 
+        sqlx::query(
+            "CREATE TABLE IF NOT EXISTS theme (
+                id INTEGER PRIMARY KEY CHECK (id = 1),
+                data TEXT NOT NULL
+            )",
+        )
+        .execute(&self.pool)
+        .await?;
+
         Ok(())
     }
 }

crates/adapters/config-sqlite/src/repository/mod.rs

@@ -1,14 +1,15 @@
 mod data_sources;
 mod layout;
 mod presets;
+mod theme;
 mod users;
 mod widgets;
 
 use crate::SqliteConfigStore;
 use crate::error::SqliteConfigError;
 use domain::{
-    ConfigRepository, DataSource, DataSourceId, Layout, LayoutPreset, LayoutPresetId, User,
-    WidgetConfig, WidgetId,
+    ConfigRepository, DataSource, DataSourceId, Layout, LayoutPreset, LayoutPresetId, ThemeConfig,
+    User, WidgetConfig, WidgetId,
 };
 
 impl ConfigRepository for SqliteConfigStore {
@@ -70,6 +71,14 @@ impl ConfigRepository for SqliteConfigStore {
         self.delete_preset_impl(id).await
     }
 
+    async fn get_theme(&self) -> Result<Option<ThemeConfig>, Self::Error> {
+        self.get_theme_impl().await
+    }
+
+    async fn save_theme(&self, theme: &ThemeConfig) -> Result<(), Self::Error> {
+        self.save_theme_impl(theme).await
+    }
+
     async fn get_user_by_username(&self, username: &str) -> Result<Option<User>, Self::Error> {
         self.get_user_by_username_impl(username).await
     }

crates/adapters/config-sqlite/src/repository/theme.rs

@@ -0,0 +1,37 @@
+use crate::SqliteConfigStore;
+use crate::error::SqliteConfigError;
+use crate::serialization::theme as ser;
+use domain::ThemeConfig;
+use sqlx::Row;
+
+impl SqliteConfigStore {
+    pub(crate) async fn get_theme_impl(&self) -> Result<Option<ThemeConfig>, SqliteConfigError> {
+        let row = sqlx::query("SELECT data FROM theme WHERE id = 1")
+            .fetch_optional(&self.pool)
+            .await
+            .map_err(SqliteConfigError::Sql)?;
+
+        match row {
+            None => Ok(None),
+            Some(row) => {
+                let json: String = row.get("data");
+                Ok(Some(ser::theme_from_json(&json)?))
+            }
+        }
+    }
+
+    pub(crate) async fn save_theme_impl(
+        &self,
+        theme: &ThemeConfig,
+    ) -> Result<(), SqliteConfigError> {
+        let json = ser::theme_to_json(theme)?;
+
+        sqlx::query("INSERT OR REPLACE INTO theme (id, data) VALUES (1, ?)")
+            .bind(&json)
+            .execute(&self.pool)
+            .await
+            .map_err(SqliteConfigError::Sql)?;
+
+        Ok(())
+    }
+}

crates/adapters/config-sqlite/src/serialization/layout.rs

@@ -1,5 +1,7 @@
 use crate::error::SqliteConfigError;
-use domain::{AlignItems, ContainerNode, Direction, JustifyContent, Layout, LayoutChild, LayoutNode, Sizing};
+use domain::{
+    AlignItems, ContainerNode, Direction, JustifyContent, Layout, LayoutChild, LayoutNode, Sizing,
+};
 
 pub fn layout_to_json(layout: &Layout) -> Result<String, SqliteConfigError> {
     let v = node_to_json(&layout.root);
@@ -37,6 +39,19 @@ fn node_to_json(node: &LayoutNode) -> serde_json::Value {
                 "direction": match c.direction { Direction::Row => "row", Direction::Column => "column" },
                 "gap": c.gap,
                 "padding": c.padding,
+                "justify_content": match c.justify_content {
+                    JustifyContent::Start => "start",
+                    JustifyContent::Center => "center",
+                    JustifyContent::End => "end",
+                    JustifyContent::SpaceBetween => "space_between",
+                    JustifyContent::SpaceEvenly => "space_evenly",
+                },
+                "align_items": match c.align_items {
+                    AlignItems::Start => "start",
+                    AlignItems::Center => "center",
+                    AlignItems::End => "end",
+                    AlignItems::Stretch => "stretch",
+                },
                 "children": children,
             })
         }
@@ -93,12 +108,26 @@ fn node_from_json(v: &serde_json::Value) -> Result<LayoutNode, SqliteConfigError
                 })
                 .collect::<Result<Vec<_>, _>>()?;
 
+            let justify_content = match v["justify_content"].as_str() {
+                Some("center") => JustifyContent::Center,
+                Some("end") => JustifyContent::End,
+                Some("space_between") => JustifyContent::SpaceBetween,
+                Some("space_evenly") => JustifyContent::SpaceEvenly,
+                _ => JustifyContent::Start,
+            };
+            let align_items = match v["align_items"].as_str() {
+                Some("center") => AlignItems::Center,
+                Some("end") => AlignItems::End,
+                Some("stretch") => AlignItems::Stretch,
+                _ => AlignItems::Start,
+            };
+
             Ok(LayoutNode::Container(ContainerNode {
                 direction,
                 gap,
                 padding,
-                justify_content: JustifyContent::Start,
-                align_items: AlignItems::Stretch,
+                justify_content,
+                align_items,
                 children,
             }))
         }

crates/adapters/config-sqlite/src/serialization/mod.rs

@@ -1,4 +1,5 @@
 pub mod data_source;
 pub mod layout;
 pub mod preset;
+pub mod theme;
 pub mod widget;

crates/adapters/config-sqlite/src/serialization/theme.rs

@@ -0,0 +1,40 @@
+use crate::error::SqliteConfigError;
+use domain::{ThemeColor, ThemeConfig};
+
+pub fn theme_to_json(theme: &ThemeConfig) -> Result<String, SqliteConfigError> {
+    let v = serde_json::json!({
+        "primary": color_to_json(&theme.primary),
+        "secondary": color_to_json(&theme.secondary),
+        "accent": color_to_json(&theme.accent),
+        "text": color_to_json(&theme.text),
+        "background": color_to_json(&theme.background),
+    });
+    serde_json::to_string(&v).map_err(|e| SqliteConfigError::Serialization(e.to_string()))
+}
+
+pub fn theme_from_json(json: &str) -> Result<ThemeConfig, SqliteConfigError> {
+    let v: serde_json::Value =
+        serde_json::from_str(json).map_err(|e| SqliteConfigError::Serialization(e.to_string()))?;
+    let err = |msg: &str| SqliteConfigError::Serialization(msg.into());
+
+    Ok(ThemeConfig {
+        primary: color_from_json(&v["primary"]).map_err(|_| err("invalid primary"))?,
+        secondary: color_from_json(&v["secondary"]).map_err(|_| err("invalid secondary"))?,
+        accent: color_from_json(&v["accent"]).map_err(|_| err("invalid accent"))?,
+        text: color_from_json(&v["text"]).map_err(|_| err("invalid text"))?,
+        background: color_from_json(&v["background"]).map_err(|_| err("invalid background"))?,
+    })
+}
+
+fn color_to_json(c: &ThemeColor) -> serde_json::Value {
+    serde_json::json!({ "r": c.r, "g": c.g, "b": c.b })
+}
+
+fn color_from_json(v: &serde_json::Value) -> Result<ThemeColor, SqliteConfigError> {
+    let err = |msg: &str| SqliteConfigError::Serialization(msg.into());
+    Ok(ThemeColor {
+        r: v["r"].as_u64().ok_or_else(|| err("missing r"))? as u8,
+        g: v["g"].as_u64().ok_or_else(|| err("missing g"))? as u8,
+        b: v["b"].as_u64().ok_or_else(|| err("missing b"))? as u8,
+    })
+}