[mvaligursky]

Do not merge until engine 2.24 is released. Shadow bounds ship with 2.24, and the new example paths only exist on the examples browser once it is deployed with 2.24. The old paths keep redirecting after that, so merging late is safe, while merging early would document an unreleased API and break the updated embeds.

Engine 2.24 adds LightComponent#shadowBounds (playcanvas/engine#9791) and moves the light and shadow examples from the graphics category of the examples browser into a new lights-and-shadows category (playcanvas/engine#9792). This documents the shadow bounds and points the user manual at the new example paths.

Changes:

• Shadows page: a new Shadow Bounds section. It covers fitting a directional light's shadow to a world space box that encloses the casters and is shared by all cameras, updating the box to follow a moving object, the cascade settings it replaces, and how it works with shadowUpdateMode. It embeds the new lights-and-shadows/shadow-bounds example
• Shadows page: Performance Considerations notes that a light with shadow bounds renders one shadow map for all cameras, and the code examples drop the pc. prefix
• The light-physical-units embed on the Tone Mapping page and the lights-baked link on the Device Loss page use the lights-and-shadows paths
• The engine llms.txt entry for the Shadows page mentions shadow bounds
• Japanese translations updated to match