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.

editor/turnouts.h

@@ -22,8 +22,11 @@ namespace editor
 struct turnout_preset
 {
 	std::string name;
-	double crossing_n;
-	double radius;
+	double crossing_n;   // skos 1:n
+	double radius;       // metres
+	double length;       // catalogue length PR->KR along the through track, metres
+	double blade_angle;  // kąt nagięcia iglicy (beta), radians; the diverging leaves the straight here
+	double pre_blade;    // odcinek przediglicowy: straight lead PR -> blade tip, metres
 };
 
 // typical Polish turnouts (rozjazdy zwyczajne). the (skos, R) pairs are the recognised standard;