- Delete src/modules/draw/modify/extend.rs (a 1-line placeholder with no
tool()/logic; `extend::` was referenced nowhere) and its `mod extend;`.
- Flatten single-file module dirs to the modern flat style:
src/command/mod.rs -> src/command.rs, src/snap/mod.rs -> src/snap.rs.
Parent `mod command;`/`mod snap;` are unchanged.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
