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/client-domain/tests/render_tree_tests.rs

@@ -0,0 +1,85 @@
+use domain::{
+    LayoutNode, ContainerNode, LayoutChild, Direction, Sizing,
+};
+use client_domain::{BoundingBox, LayoutEngine};
+
+fn screen() -> BoundingBox {
+    BoundingBox::screen(240, 320)
+}
+
+#[test]
+fn diff_detects_moved_widget_after_layout_change() {
+    let layout_a = LayoutNode::Container(ContainerNode {
+        direction: Direction::Row,
+        gap: 0,
+        padding: 0,
+        children: vec![
+            LayoutChild { sizing: Sizing::Flex(1), node: LayoutNode::Leaf(1) },
+            LayoutChild { sizing: Sizing::Flex(1), node: LayoutNode::Leaf(2) },
+        ],
+    });
+
+    let layout_b = LayoutNode::Container(ContainerNode {
+        direction: Direction::Column,
+        gap: 0,
+        padding: 0,
+        children: vec![
+            LayoutChild { sizing: Sizing::Flex(1), node: LayoutNode::Leaf(1) },
+            LayoutChild { sizing: Sizing::Flex(1), node: LayoutNode::Leaf(2) },
+        ],
+    });
+
+    let tree_a = LayoutEngine::compute(&layout_a, screen());
+    let tree_b = LayoutEngine::compute(&layout_b, screen());
+
+    let mut changed = tree_b.diff(&tree_a);
+    changed.sort();
+    assert_eq!(changed, vec![1, 2]);
+}
+
+#[test]
+fn diff_returns_empty_for_identical_layouts() {
+    let layout = LayoutNode::Container(ContainerNode {
+        direction: Direction::Row,
+        gap: 0,
+        padding: 0,
+        children: vec![
+            LayoutChild { sizing: Sizing::Flex(1), node: LayoutNode::Leaf(1) },
+            LayoutChild { sizing: Sizing::Flex(1), node: LayoutNode::Leaf(2) },
+        ],
+    });
+
+    let tree_a = LayoutEngine::compute(&layout, screen());
+    let tree_b = LayoutEngine::compute(&layout, screen());
+
+    assert!(tree_b.diff(&tree_a).is_empty());
+}
+
+#[test]
+fn diff_detects_added_and_removed_widgets() {
+    let layout_a = LayoutNode::Container(ContainerNode {
+        direction: Direction::Row,
+        gap: 0,
+        padding: 0,
+        children: vec![
+            LayoutChild { sizing: Sizing::Flex(1), node: LayoutNode::Leaf(1) },
+        ],
+    });
+
+    let layout_b = LayoutNode::Container(ContainerNode {
+        direction: Direction::Row,
+        gap: 0,
+        padding: 0,
+        children: vec![
+            LayoutChild { sizing: Sizing::Flex(1), node: LayoutNode::Leaf(2) },
+        ],
+    });
+
+    let tree_a = LayoutEngine::compute(&layout_a, screen());
+    let tree_b = LayoutEngine::compute(&layout_b, screen());
+
+    let mut changed = tree_b.diff(&tree_a);
+    changed.sort();
+    // widget 1 was removed (in old but not new), widget 2 was added (in new but not old)
+    assert_eq!(changed, vec![1, 2]);
+}