feat: add gravity and gravity-movement plugins

Add CHGravityPlugin to manage the global gravity resource and
CHGravityMovementGluePlugin to apply gravity to movement velocity
each fixed update. Update workspace dependencies and include the
new crates in the main app.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/main.rs b/src/main.rs
index 4906590..df08db9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -9,5 +9,7 @@ fn main() {
     let mut app = App::new();
     app.add_plugins(DefaultPlugins);
     app.add_plugins(ch_movement::CHMovementPlugin);
+    app.add_plugins(ch_gravity::CHGravityPlugin);
+    app.add_plugins(ch_gravity_movement::CHGravityMovementGluePlugin);
     app.run();
 }