expose h_align/v_align through full stack

display_hint becomes {kind, h_align, v_align} object in API, SQLite
gets alignment columns, SPA widget form gets alignment selects, layout
preview reflects actual alignment instead of hardcoded center

crates/adapters/config-sqlite/src/lib.rs

@@ -96,6 +96,14 @@ impl SqliteConfigStore {
         .execute(&self.pool)
         .await?;
 
+        // Add alignment columns to widgets (idempotent)
+        let _ = sqlx::query("ALTER TABLE widgets ADD COLUMN h_align TEXT NOT NULL DEFAULT 'left'")
+            .execute(&self.pool)
+            .await;
+        let _ = sqlx::query("ALTER TABLE widgets ADD COLUMN v_align TEXT NOT NULL DEFAULT 'top'")
+            .execute(&self.pool)
+            .await;
+
         Ok(())
     }
 }