nightly

Trim the image loaders (#2912)

* Trim the image loaders

Once ResourceManager took over decoding, every loader shrank to a call or two, but each still carried its own copy of the same constructor and members. They now inherit a constructor from ImageLoader, which holds the ResourceManager and the resource name.

Load(RgbaImage *) returned a bool that was true for every loader except the sprite one, which signalled failure with an empty image as well. load() now returns the image, and an empty one means the load failed, which is also the shape a size accessor on the loaders will need.

PCX_LOD_Raw_Loader and its PCX_Loader base had no users left since savegame thumbnails started decoding their PCX directly, so they are gone.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

* Follow the naming rules in ImageLoader

GetResourceName() was the last PascalCase method on ImageLoader, and the protected resource_name member was snake_case. The members are now private _resources and _name behind a public name() and a protected resources(). ImageLoader.cpp loses the string_view and Renderer.h includes it no longer uses, and OpenGLRenderer.cpp drops an ImageLoader.h include it never used.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

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Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>