arch: split ConfigRepository, extract polling, consolidate conversions, decouple protocol

- Value↔JSON: From impls on domain Value behind `json` feature, delete 4 duplicate converters
- ConfigRepository split into ConfigRepository (12), UserRepository (3), WidgetStateCache (2)
- polling orchestration moved from bootstrap to application::polling_service
- WidgetRenderer in client-domain owns scroll/cache, both clients use it
- network loop consolidated into client-application::run_connection_loop
- protocol crate drops domain dep, Wire↔Domain conversions move to adapters

crates/domain/src/ports/config_repository.rs

@@ -1,7 +1,7 @@
 use crate::entities::{
-    DataSource, DataSourceId, LayoutPreset, LayoutPresetId, User, WidgetConfig, WidgetId,
+    DataSource, DataSourceId, LayoutPreset, LayoutPresetId, WidgetConfig, WidgetId,
 };
-use crate::value_objects::{Layout, ThemeConfig, WidgetState};
+use crate::value_objects::{Layout, ThemeConfig};
 use std::future::Future;
 
 pub trait ConfigRepository {
@@ -56,19 +56,4 @@ pub trait ConfigRepository {
         &self,
         theme: &ThemeConfig,
     ) -> impl Future<Output = Result<(), Self::Error>> + Send;
-
-    fn get_user_by_username(
-        &self,
-        username: &str,
-    ) -> impl Future<Output = Result<Option<User>, Self::Error>> + Send;
-    fn save_user(&self, user: &User) -> impl Future<Output = Result<(), Self::Error>> + Send;
-    fn count_users(&self) -> impl Future<Output = Result<u32, Self::Error>> + Send;
-
-    fn save_widget_states(
-        &self,
-        states: &[(WidgetId, WidgetState)],
-    ) -> impl Future<Output = Result<(), Self::Error>> + Send;
-    fn load_widget_states(
-        &self,
-    ) -> impl Future<Output = Result<Vec<(WidgetId, WidgetState)>, Self::Error>> + Send;
 }

crates/domain/src/ports/mod.rs

@@ -5,6 +5,8 @@ mod config_repository;
 mod data_source_port;
 mod event;
 mod secret_store;
+mod user_repository;
+mod widget_state_cache;
 mod widget_state_reader;
 
 pub use auth::{AuthPort, PasswordHashPort};
@@ -14,4 +16,6 @@ pub use config_repository::ConfigRepository;
 pub use data_source_port::DataSourcePort;
 pub use event::EventPublisher;
 pub use secret_store::SecretStore;
+pub use user_repository::UserRepository;
+pub use widget_state_cache::WidgetStateCache;
 pub use widget_state_reader::WidgetStateReader;

crates/domain/src/ports/user_repository.rs

@@ -0,0 +1,13 @@
+use crate::entities::User;
+use std::future::Future;
+
+pub trait UserRepository {
+    type Error;
+
+    fn get_user_by_username(
+        &self,
+        username: &str,
+    ) -> impl Future<Output = Result<Option<User>, Self::Error>> + Send;
+    fn save_user(&self, user: &User) -> impl Future<Output = Result<(), Self::Error>> + Send;
+    fn count_users(&self) -> impl Future<Output = Result<u32, Self::Error>> + Send;
+}

crates/domain/src/ports/widget_state_cache.rs

@@ -0,0 +1,15 @@
+use crate::entities::WidgetId;
+use crate::value_objects::WidgetState;
+use std::future::Future;
+
+pub trait WidgetStateCache {
+    type Error;
+
+    fn save_widget_states(
+        &self,
+        states: &[(WidgetId, WidgetState)],
+    ) -> impl Future<Output = Result<(), Self::Error>> + Send;
+    fn load_widget_states(
+        &self,
+    ) -> impl Future<Output = Result<Vec<(WidgetId, WidgetState)>, Self::Error>> + Send;
+}