forked from 1b-agent/opencadstudio-upstream
Tests previously ran on Ubuntu only, so Windows- and macOS-specific breakage went unseen. Add a 3-OS test matrix and a separate lint job for rustfmt and clippy. Lint is continue-on-error because the tree is not yet fmt-clean or clippy-clean. Also add BEDIT characterization tests that pin current session, undo and refusal behavior ahead of the editor refactor. Locked tests guard behavior that must survive; documenting tests record questionable behavior expected to change.