Use Blueprinted screenshots, drop 360 view, and fix release flow

[uberswe]

• Remove the 360 rotation render: always render just the 4 isometric views, drop the render360/frameCount/saveAllFrames config options and the rotation_images upload parts
• Rework the Create: Blueprinted integration for the 2.2.2 ShareProvider API: keep Blueprinted's own share button, let it render the screenshot and upload it with the schematic via onRender's Future; the save-prompt flow also routes through Blueprinted's renderer when installed, falling back to our renderer otherwise
• Register the share provider in FMLClientSetupEvent instead of the mod constructor to avoid load-order issues, and require Blueprinted 2.2.2+
• Bump mod_version to 2.2.0, make the release workflow commit the released version back to the branch, and build 1.21.1 releases from main instead of the stale mc/1.21.1 branch