Desktop: Isolate CEF-rendered UI into separate crate and process (#4321)

* Extract CEF rendered UI into a separate process and crate

* Review

* Review

* Review

* Review

* Remove necessary workarounds

* Block on frame copy ack

* Crop and resample frames correctly

* Skip blank frames

* Fix deps

* Fix fmt

* Fix clippy warning

* Review

* Fix todo

desktop/platform/linux/src/main.rs

@@ -1,3 +1,3 @@
-fn main() {
-	graphite_desktop::start();
+fn main() -> std::process::ExitCode {
+	graphite_desktop::start()
 }

desktop/platform/mac/Cargo.toml

@@ -8,13 +8,20 @@ repository = ""
 edition = "2024"
 rust-version = "1.87"
 
+[features]
+main = ["dep:graphite-desktop"]
+helper = ["dep:graphite-desktop-ui"]
+
 [[bin]]
 name = "graphite"
 path = "src/main.rs"
+required-features = ["main"]
 
 [[bin]]
 name = "helper"
 path = "src/helper.rs"
+required-features = ["helper"]
 
 [dependencies]
-graphite-desktop = { path = "../.." }
+graphite-desktop = { path = "../..", optional = true }
+graphite-desktop-ui = { path = "../../ui", optional = true }

desktop/platform/mac/src/helper.rs

@@ -1,3 +1,3 @@
-fn main() {
-	graphite_desktop::start_helper();
+fn main() -> std::process::ExitCode {
+	graphite_desktop_ui::run_helper()
 }

desktop/platform/mac/src/main.rs

@@ -1,3 +1,3 @@
-fn main() {
-	graphite_desktop::start();
+fn main() -> std::process::ExitCode {
+	graphite_desktop::start()
 }

desktop/platform/win/src/main.rs

@@ -1,4 +1,4 @@
 #![windows_subsystem = "windows"]
-fn main() {
-	graphite_desktop::start();
+fn main() -> std::process::ExitCode {
+	graphite_desktop::start()
 }