Show the bottom, left, top, right Gmsh tag order

Update the Gmsh examples on the Mesh page, the importGmshMesh Node.js
example and llms.txt, so Gmsh meshes get the same boundary keys as
structured meshes.

Author: nikoscham

docs/api/gmsh-import.md

@@ -63,10 +63,10 @@ const model = new FEAScriptModel();
 model.setModelConfig("heatConductionScript");
 model.setMeshConfig({ parsedMesh });
 
-model.addBoundaryCondition("0", ["constantTemperature", 200]); // Physical curve with tag 1
-model.addBoundaryCondition("1", ["constantTemperature", 200]); // Physical curve with tag 2
-model.addBoundaryCondition("2", ["convection", 1, 20]); // Physical curve with tag 3
-model.addBoundaryCondition("3", ["symmetry"]); // Physical curve with tag 4
+model.addBoundaryCondition("0", ["constantTemperature", 200]); // Physical curve "bottom", tag 1
+model.addBoundaryCondition("1", ["symmetry"]); // Physical curve "left", tag 2
+model.addBoundaryCondition("2", ["convection", 1, 20]); // Physical curve "top", tag 3
+model.addBoundaryCondition("3", ["constantTemperature", 200]); // Physical curve "right", tag 4
 
 const { solutionVector, nodesCoordinates } = model.solve();
 ```

docs/fundamentals/mesh.md

@@ -135,16 +135,20 @@ They are numbered in increasing order of their physical tag, starting from key `
 have the tags `1`, `2`, ..., the boundary key is the tag minus one. 2D physical groups (for example a
 `Physical Surface`) do not define boundaries.
 
-For example, with the following `.geo` definitions:
+To get the same keys as a [structured mesh](#boundaries-of-a-structured-mesh), tag the sides in the order
+bottom, left, top, right. For a rectangle whose lines 1, 2, 3, 4 are the bottom, right, top and left sides:
 
 ```
-Physical Line("bottom") = {1}; // tag 1 → boundary key "0"
-Physical Line("right")  = {2}; // tag 2 → boundary key "1"
-Physical Line("top")    = {3}; // tag 3 → boundary key "2"
-Physical Line("left")   = {4}; // tag 4 → boundary key "3"
-Physical Surface("domain") = {1};
+Physical Line("bottom", 1) = {1}; // tag 1 → boundary key "0"
+Physical Line("left", 2)   = {4}; // tag 2 → boundary key "1"
+Physical Line("top", 3)    = {3}; // tag 3 → boundary key "2"
+Physical Line("right", 4)  = {2}; // tag 4 → boundary key "3"
+Physical Surface("domain", 5) = {1};
 ```
 
+The second argument of `Physical Line` sets the tag explicitly. Without it, Gmsh numbers the groups in the order they
+are defined.
+
 Generate the mesh in the supported format with:
 
 ```bash

static/llms.txt

@@ -173,7 +173,7 @@ model.setMeshConfig({ parsedMesh }); // meshDimension and elementOrder are detec
 ```
 
 - Supported: `.msh` version 4.1 ASCII (`gmsh model.geo -2 -format msh41 -o model.msh`), 2D only, all quadrilaterals or all triangles, all linear or all quadratic.
-- Boundary keys come from the 1D physical groups (`Physical Curve` / `Physical Line`), numbered in increasing tag order from `"0"`: tags 1, 2, 3, 4 → keys `"0"`, `"1"`, `"2"`, `"3"`.
+- Boundary keys come from the 1D physical groups (`Physical Curve` / `Physical Line`), numbered in increasing tag order from `"0"`: tags 1, 2, 3, 4 → keys `"0"`, `"1"`, `"2"`, `"3"`. Tag the sides bottom, left, top, right (e.g. `Physical Line("left", 2) = {4};`) to get the same keys as a structured mesh.
 
 ## Boundary condition rules