Add resolved appearance engine and paired theme settings

Resolve light, dark and automatic appearance centrally and publish live theme snapshots to native surfaces and the appearance portal. Add paired preset families, custom theme imports, accessibility transforms and contrast-safe transitions.

Refine the Settings gallery and Auto controls, move overrides under advanced customization, and share palette-aware switches and circular slider thumbs. Document configuration and include theme licenses and integration coverage.

crates/ferese-theme/src/service.rs

@@ -0,0 +1,57 @@
+use cosmic::iced::futures::SinkExt;
+use ferese_config::theme::Snapshot;
+
+pub fn current() -> Snapshot {
+    ferese_ipc::theme::current()
+}
+
+pub fn opacity(theme: &ferese_config::theme::ResolvedTheme) -> f32 {
+    if theme.tokens.material.style == "translucent" {
+        theme.tokens.material.opacity as f32
+    } else {
+        1.
+    }
+}
+
+pub fn subscription() -> cosmic::iced::Subscription<Snapshot> {
+    cosmic::iced::Subscription::run(stream)
+}
+
+fn stream() -> impl cosmic::iced::futures::Stream<Item = Snapshot> {
+    cosmic::iced::stream::channel(1, async |mut output| {
+        loop {
+            let connection = tokio::task::spawn_blocking(ferese_ipc::theme::Connection::connect).await;
+            let Ok(Ok(mut connection)) = connection else {
+                tokio::time::sleep(std::time::Duration::from_secs(1)).await;
+                continue;
+            };
+            let Ok(cancellation) = connection.cancellation() else {
+                return;
+            };
+            let (send, mut receive) = tokio::sync::watch::channel(None);
+            tokio::task::spawn_blocking(move || {
+                let Ok(mut snapshot) = connection.get() else { return };
+                loop {
+                    let revision = snapshot.revision;
+                    if send.send(Some(snapshot)).is_err() {
+                        return;
+                    }
+                    match connection.watch(revision) {
+                        Ok(next) => snapshot = next,
+                        Err(_) => return,
+                    }
+                }
+            });
+            while receive.changed().await.is_ok() {
+                let snapshot = receive.borrow_and_update().clone();
+                if let Some(snapshot) = snapshot {
+                    if output.send(snapshot).await.is_err() {
+                        return;
+                    }
+                }
+            }
+            drop(cancellation);
+            tokio::time::sleep(std::time::Duration::from_secs(1)).await;
+        }
+    })
+}