Material/texture separation, usability improvements, new features and fixes

[funcmathias]

Hey Bill, found this a few months ago when looking for a proper texture browser for CSG, and I quite like it!
From the perspective of a new user there were a few things that felt like it could be improved and clearer however (main thing being that materials and textures showed up the same), and that's mainly where my changes started, but I ended up enjoying toying with it and suddenly I had amassed a lot of changes, fixes and even new features. Thought I'd share it with the world since I ended up doing so much, hopefully it's useful!

I tried to make my changes quite general but there may be some subjective changes you do not agree with (like the menu location, or some of the visual changes), I'm happy to discuss and change/revert some of those if needed if you like the overall package and want most of it in.
Also please excuse this being a single large commit, but due to the sporadic nature of how it developed I have no good commit history for it heh..

Here's a video demonstrating how it looks and functions in this PR, and under I've added the change log which should cover most of the changes, it's a lot so I might've missed some stuff. (Here's the texture pack I tested with as well.)

2025-October-22.16-40-59.Unity-1.mp4

Fixes:

• Fixed texture browser not loading if the window is open when Unity boots up.
• Fixed blank saved search that appears when there's no saved searches.
• Fixed error that appears when a material doesn't have a _MainTex property.

Changes/improvements:

• Moved texture name label to be under the texture so it's unobstructed, and added ellipsis on text overflow.
• Added an icon to texture label showing if a thumbnail is for a material or a texture without a material. The icon goes from blue to yellow if it's favourited.
• Added text at the bottom of the window that shows the full path and resolution of the texture you're hovering over. Also made the thumbnail size slider much smaller to make room for this.
• Made the buttons that appear when hovering over a texture be transparent until you specifically hover over them too. And adjusted their size and icon size.
• If a thumbnail is for a raw texture, the hover button to "locate material" will instead create a material for that texture, and the text and icon is changed to reflect that. If pressed the thumbnail will be refreshed to reflect now being a material.
• Added filter buttons to show textures or materials separately.
• Searching now checks both the texture name and the material name for matches.
• Sorting now ignores case, makes more sense to me at least.
• Changed menu position to be inside the "Window" menu instead of "LEG", feels like a better placement for the average person. (If keeping "LEG" is strongly desired I'd suggest having it as a sub menu inside the "window" dropdown at least.)
• Changed default shader main tex keyword from "_BaseMap to "_MainTex" which is the default for Unity.
• Took border width into account for overall preview element size (borders would shrink the texture to be displayed as 126 instead of 128 for example).
• Changed how TextureInfo works to be slightly more convenient and fill in more of its info automatically.
• Changed the icon of "show used in scenes" from a brush to something I felt was a bit better, though it's very subjective and there wasn't many choices that would really fit.
• Made the X in the search field a bit bigger to be easier to click.

New stuff:

• Added a checkerboard background to better show if textures are transparent, it gets hidden when hovering over the texture. If the texture is non-square the checkers will only render behind its bounding box to ensure the aspect of the texture is clear.
• Added user setting to change the tint of the checkered background, which also includes opacity.
• Non-square textures will be zoomed in to fill the square when hovering over so you can see details better, it also pans across when moving the mouse from one side to another, this can be disabled in user settings.