Desktop builds with their own profile: thin LTO and 16 codegen units, compiled on all cores

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Cargo.toml

@@ -18,6 +18,14 @@ codegen-units = 1
 [profile.dev]
 opt-level = 1
 
+# desktop builds (tools/build_desktop.py): optimised like release, but compiled on all cores
+# (several codegen units, thin LTO); release keeps one unit and full LTO for the smallest,
+# fastest WASM
+[profile.desktop]
+inherits = "release"
+lto = "thin"
+codegen-units = 16
+
 # desktop builds: system file dialog (xdg portal on Linux) and sound output
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 rfd = { version = "0.17", default-features = false, features = ["xdg-portal"] }