Fix transform gizmo drag using stale camera / transform state

[mufeng1991]

Fix transform gizmo drag by running hover/drag after transform propagation and camera updates.

Prior ordering caused viewport_to_world to use stale camera state; also default confine_cursor to false to avoid unreliable cursor_position during drags.

Objective

• Fix unreliable transform gizmo dragging (e.g. axis handles feeling like they “lose” input shortly after press, or the manipulated entity not tracking the cursor smoothly).
• Align gizmo interaction with the documented contract for Camera::viewport_to_world: use an up-to-date GlobalTransform and camera computed state when casting pointer rays each frame.

Solution

• Schedule transform_gizmo_hover and transform_gizmo_drag after TransformSystems::Propagate and CameraUpdateSystems, and run hover before drag in the same frame so hovered_axis matches the current cursor before just_pressed starts a drag.
• transform_gizmo_hover: return early when TransformGizmoState::active before clearing hovered_axis, so drag state is not wiped at the start of the hover system while a drag is in progress.
• TransformGizmoSettings::confine_cursor: default to false and document that CursorGrabMode::Confined can make Window::cursor_position() unreliable on some platforms, which breaks per-frame viewport_to_world during drags. Apps that want confinement can still set confine_cursor: true.

Testing

• Ran cargo check -p bevy_gizmos.
• Manually ran cargo run --example transform_gizmo --features free_camera (and any app using TransformGizmoPlugin): select an entity, drag translate/rotate/scale axes and view handles; confirm motion stays consistent for the whole press–drag–release cycle.
• Reviewers: same as above; no special assets. Compare with main: if drag used to stall or jump when moving the camera (e.g. fly camera) while dragging, this branch should improve ray consistency.
• Platforms: tested on <your OS>. Cannot test on Linux Wayland / Windows ARM / web; if anyone sees cursor issues with confine_cursor: true, that remains an opt-in path.

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Migration Guide

• If you relied on cursor confinement during gizmo drags, set transform_gizmo_settings.confine_cursor = true after plugin init (defaults are now false for robustness).

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[alice-i-cecile]

The PR description doesn't match the code at all. Can you please rewrite it to clearly explain your changes?