The Extension object snap worked but drew no tracking path, so it was
easy to miss — users had to keep the cursor exactly on the invisible
extension line without any visual cue.
When an Extension snap is active, draw a dashed guide line from the
endpoint it extends from, through the snap point and a little beyond,
and orient the three-dot marker along that direction. SnapResult carries
the endpoint screen position (filled once the winning snap is known);
the overlay renders the guide.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
- 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 <[email protected]>
