Fix config upgrade failures, save races, lock confirmation and release validation (#23)

* Coordinate config writes and gate releases on desktop validation

* Use toolkit rc.2 with painting and session lock fixes

* Ignore retired desktop widget settings in existing configs

crates/ferese-config/Cargo.toml

@@ -11,6 +11,4 @@ jiff.workspace = true
 kdl = "6.7.1"
 serde.workspace = true
 serde_json.workspace = true
-
-[dev-dependencies]
 tempfile.workspace = true