Streets: sidewalks, road curves, junctions and roundabouts

Roads take sidewalks (none, both, left, right): 12 cm high paving with
kerb faces drawn where they face the viewer. Road curve (radius, angle,
left/right) carries a street round a bend; centre lines are true arcs
when cut and offset, so curve joints are seamless. A road ending on
another road's centre line opens that road's kerb and sidewalk (T
junction); two roads ending at one corner close it. Roundabout: ring
radius and width, one or two lanes, up to four arms with flared kerbs,
splitter islands, give-way lines on the entry side (traffic on the left
or right) and a central island with apron.

Studio: a road run drawn corner by corner gets a curve in each corner
(prefab meta `corner`). Tooltips list the streets each one meets.
Engine: open `polyline` primitive (Prim::Poly open) so dashes run on
round curves. examples/streets and a Streets demo in the web Studio;
MCP guidance, docs. ROADMAP: backlog 5-7 done; multi-select and the
hosted copy marked done.

Tests: Rust 72, Studio 113, web 95.

docs/ROADMAP.md

@@ -34,7 +34,8 @@ Each phase ends with tests, a Studio/viewer check in Edge, commit and push.
 - [x] Code editor for scripts, prefabs, theme and manifest, with script errors by file and line
 - [x] MCP tools inside the page (`isokit.mcp`), WebMCP registration when the browser offers it
 - [x] `tools/build_web.py` (static output), `tools/check_web.py` (44 checks, Edge)
-- [ ] Deploy a hosted copy; render in a Web Worker for very large scenes
+- [x] Hosted copy at https://isokit.buildfor.life/ (deployed by `.gitea/workflows/deploy-web.yml`)
+- [ ] Render in a Web Worker for very large scenes
 
 ## Agent window (done)
 
@@ -75,9 +76,9 @@ Each phase ends with tests, a Studio/viewer check in Edge, commit and push.
 2. ~~Conveyors~~ (done, see below)
 3. ~~Producers with adjustable production speed~~ (done, see below)
 4. ~~Robotic arms~~ (done, see below)
-5. Rounded streets: curved road segments
-6. Sidewalks along streets
-7. Roundabouts
+5. ~~Rounded streets: curved road segments~~ (done, see below)
+6. ~~Sidewalks along streets~~ (done, see below)
+7. ~~Roundabouts~~ (done, see below)
 8. Waypoint animation: a person or car moving along a path of waypoints
 9. ~~Build your own house~~ (done, see above)
 
@@ -108,12 +109,23 @@ another belt or on a pallet, one move per item (or a set cycle), waiting while t
 stands; the belt after it runs in step. Drawn as a 16-pose flipbook (inverse kinematics, links as
 the new native `beam` primitive) shown by a stepped CSS animation.
 
+Streets (stdlib/streets.rhai): roads take sidewalks (none, both, left, right; 12 cm high paving with
+kerb faces); Road curve (radius, angle, left / right) carries a street round a bend, its kerbs and
+sidewalks drawn as true arcs so the joints are seamless; a road ending on another road's centre
+line opens that road's kerb and sidewalk (T junction); two roads ending at one corner close it.
+Roundabout: ring radius and width, one or two lanes, up to four arms with flared kerbs, splitter
+islands and give-way lines on the entry side (traffic on the left or right), central island with
+apron (tree, grass or paved). A road run drawn corner by corner gets a curve in each corner (prefab
+meta `corner`). Tooltips list the streets each one meets. New `polyline` primitive (open paths, so
+dashes run on round curves). `examples/streets`, Streets demo in the web Studio.
+
 ## Phase 2: richer editing
 
 - [x] Interior prefabs (see Build your own house); a building `rooms` prop is still open
 - [ ] Path objects in the Studio: click points for areas, roads (polyline with width), fences, walls,
       pipe runs; vertex handles
-- [ ] Multi-select (box select, Shift-click), group move, align/distribute
+- [x] Multi-select (box select, Ctrl+click, Shift range), group move, turn, copy, delete, edit
+- [ ] Align / distribute the selection
 - [ ] Copy/paste between projects; prefab thumbnails in the palette (rendered icons)
 - [ ] Measure tool and grid overlay; numeric resize handles on the selection
 - [ ] Studio editor for `theme.toml` (colour pickers) and for project parameters