Revert C1 surface algorithm to simple ID-based ordering

[Copilot]

The C1 surface creation algorithm was modified to use centroid-based polygon detection with inner/outer point separation, which didn't match expected behavior. Users expect simple sequential connections based on point IDs.

Changes

• Reverted CreateurSurfaceC1::creerSurfaces() to original algorithm: sort points by ID, connect sequentially, close polygon

// Before: complex centroid/angle-based polygon with inner point connections
// After: simple ID-ordered closed polygon
sort(pts.begin(), pts.end(), [](Point* a, Point* b){ return a->getId() < b->getId(); });
for (size_t i = 0; i + 1 < pts.size(); ++i) {
    segs.push_back({ pts[i]->x(), pts[i]->y(), pts[i+1]->x(), pts[i+1]->y() });
}
segs.push_back({ pts.back()->x(), pts.back()->y(), pts.front()->x(), pts.front()->y() });

The nuage display format changes (using "elements" vs "points" based on content type) are preserved.

Original prompt

remet l'algorithme de dessin de c1 la modification que tu as fait ne correspond pas a mes attentes a l'execution mais l'Autre que tu as faite pour avoir > a
Liste:
0: (2,0) textures: 'o#'
1: (28,8) textures: '#'
2: (28,0) textures: '#'
3: (2,8) textures: 'o#'
4: (15,16) textures: 'o#'
5: Nuage 'o' contient les points: 0 3 4
6: Nuage '#' contient les elements: 1 2 5 est correcte

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