Macos space mouse support (#1815)

Thanks @NecroKote.

README.md

@@ -219,7 +219,7 @@ unaccepted artwork Open; run `cargo xtask icons` to check the collection.
 
 Windows builds: `cargo xwin build --release --target x86_64-pc-windows-msvc -p solidcraft`.
 
-On Windows and Linux, SolidCraft detects a connected 3D mouse through its HID multi-axis
+On Windows, macOS and Linux, SolidCraft detects a connected 3D mouse through its HID multi-axis
 controller interface: a 3Dconnexion SpaceNavigator or SpaceMouse, or a homemade device that
 declares itself one. Move the cap to pan and zoom, and tilt or twist it to rotate the 3D view.
 While editing a sketch, the cap pans and zooms without changing the sketch view. The Navigation
@@ -257,6 +257,13 @@ lays them out: translation and rotation in separate reports (3Dconnexion's wired
 in one (its wireless ones and most homemade devices), after the buttons, or narrower than 16 bits.
 Each axis is scaled from the range the descriptor declares.
 
+On macOS SolidCraft talks to the 3Dconnexion driver (3DxWare) when it is installed, through the
+driver's client API (`crates/threedx-client`; the framework is loaded at run time, never bundled).
+The driver keeps the device to itself, and sends it only to a program it can identify: SolidCraft
+as an `.app` (the packaged app). Without the driver, or with its helper not running, SolidCraft reads the device through IOKit like on Windows.
+
+SolidCraft does not follow 3DxWare's profile on macOS. Its default is 3DxWare's object mode.
+
 In the browser: `cd apps/solidcraft-web && trunk build --release --public-url ./` (WebGPU, or
 WebGL2 with `?webgl`; `?sample` opens the sample part).