add all crates: domain, protocol, application, client, adapters, ESP32 firmware

Server: domain (entities, value objects, ports), protocol (postcard wire types),
application (config service, data projection), adapters (config-memory, tcp-server),
bootstrap (composition root with fake data).

Client: client-domain (layout engine, render tree, HAL ports),
client-application (message handling, repaint commands),
adapters (tcp-client, display-terminal), client-desktop (end-to-end working).

ESP32: client-esp32 firmware with ILI9341 display over SPI, WiFi networking.
Display test verified on hardware — landscape orientation, text rendering works.

60 workspace tests, all passing.

crates/domain/src/lib.rs

@@ -0,0 +1,19 @@
+#![allow(async_fn_in_trait)]
+
+pub mod entities;
+pub mod value_objects;
+pub mod events;
+pub mod ports;
+
+pub use entities::{
+    WidgetConfig, WidgetId,
+    DataSource, DataSourceId, DataSourceType, DataSourceConfig, DataSourceValidationError,
+    LayoutPreset, LayoutPresetId,
+};
+pub use value_objects::{
+    Value, KeyMapping,
+    WidgetState, WidgetError, DisplayHint,
+    Layout, LayoutNode, LayoutChild, ContainerNode, Direction, Sizing, LayoutValidationError,
+};
+pub use events::DomainEvent;
+pub use ports::{ConfigRepository, DataSourcePort, BroadcastPort, EventPublisher};