Merge PR #1106: thicken surfaces with exact kernel geometry

Use the maintained cadkernel main revision and retain source surfaces. Verify signed and two-point input, partial failure, DWG round-trips and one-step undo/redo of solids and history objects.

Cargo.toml

@@ -32,7 +32,7 @@ rfd = "0.17"
 clap = { version = "4", features = ["derive", "string"] }
 env_logger = "0.11"
 acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "62628c41670a914d1598a14faafc3c6e3aa4a270", features = ["serde"] }
-cadkernel = { git = "https://github.com/HakanSeven12/cadkernel.git", rev = "f760c46d028d4ea9d4a9834b11e9a85d9d316ad3", features = ["acis", "offset"] }
+cadkernel = { git = "https://github.com/HakanSeven12/cadkernel.git", rev = "7f18223c66c1fde2e2a2c16e61259655d173bf4f", features = ["acis", "offset"] }
 dwg-thumbnailer = { path = "crates/dwg-thumbnailer" }
 flate2 = "1"
 image = { version = "0.25", default-features = false, features = ["png", "jpeg", "bmp", "tiff"] }