Editor checkpoint: turnout domain service, web->editor rename, Id-1 templates

Checkpoint of the editor branch so work isn't carried loose across a branch
switch. Builds.

- maj0sted turnout geometry moved into the domain: domain::lay_turnout lays the
  diverging path (pre-blade lead, blade at beta, arc of alfa-beta, frog rail) and
  solve_junction is a thin adapter onto it.
- the maj0sted web/ tree renamed to editor/ (namespace and paths) - there is no
  WASM here, it's plain native C++ the editor calls.
- click places the switch at its start (początek rozjazdu); the branch's leaving
  straight is locked tangent to the frog; switches can be slid along the through
  track and flipped L/P.
- Polish turnout templates carry catalogue length (Id-1-consistent lengths), plus
  blade-angle and pre-blade fields (left 0 until the catalogue figures are in).
- TURNOUT_SPEC.md: the Bezier-based runtime/model contract.
- also folds in other pending branch changes (scenery, tests) to leave a clean tree.

maj0sted/CMakeLists.txt

@@ -31,15 +31,19 @@ add_library(maj0sted STATIC
     src/domain/parallelism_service.cpp
     src/domain/fitting_service.cpp
     src/domain/gap_fitter.cpp
+    src/domain/turnout.cpp
     src/io/project_serializer.cpp
     src/io/svg_writer.cpp
+    src/io/scn_export.cpp
     src/render/plan_sampler.cpp
     src/render/rail_renderer.cpp
-    src/web/solve.cpp
-    src/web/editor.cpp
-    src/web/ribbon.cpp
-    src/web/tile_cache.cpp
+    src/editor/solve.cpp
+    src/editor/editor.cpp
+    src/editor/ribbon.cpp
+    src/editor/tile_cache.cpp
     src/app/editor_document.cpp
+    src/app/straight_constraints.cpp
+    src/app/basket_draft.cpp
 )
 add_library(maj0sted::maj0sted ALIAS maj0sted)