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/tests/key_mapping_tests.rs

@@ -0,0 +1,33 @@
+use std::collections::BTreeMap;
+use domain::{KeyMapping, Value};
+
+#[test]
+fn extracts_value_at_path_and_renames_key() {
+    let mapping = KeyMapping {
+        source_path: "$.main.temp".into(),
+        target_key: "temperature".into(),
+    };
+
+    let raw = Value::Object(BTreeMap::from([
+        ("main".into(), Value::Object(BTreeMap::from([
+            ("temp".into(), Value::Number(5.4)),
+        ]))),
+    ]));
+
+    let result = mapping.extract(&raw);
+    assert_eq!(result, Some(("temperature".into(), Value::Number(5.4))));
+}
+
+#[test]
+fn returns_none_when_path_does_not_match() {
+    let mapping = KeyMapping {
+        source_path: "$.missing.path".into(),
+        target_key: "value".into(),
+    };
+
+    let raw = Value::Object(BTreeMap::from([
+        ("other".into(), Value::Number(1.0)),
+    ]));
+
+    assert_eq!(mapping.extract(&raw), None);
+}