fix: resolve merge conflicts, keep test-branch rope physics

The merge of main into test (fd39db8) was committed with conflict markers
still in the files, leaving rope_tether.gd and 3dlevel.tscn unparseable
while git reported a clean tree.

Both sides were competing full implementations of the tether rather than
overlapping edits, so every hunk had to go one way. Kept the test side:
elastic leash, kinematic tautening, haul drag and the mid-chain snap.
Dropped main's _constrain/_haul/_damp/_snap port and its tension_start,
pull_speed and snap_length exports. The two scene hunks followed from the
same choice, since the rope node's properties name exports that exist on
only one side.

Also drops rope_diag.gd, which came in with that commit and drives the
discarded API (can_snap, taut_margin).

Co-Authored-By: Claude Opus 5 <[email protected]>

scenes/game_scene/levels/3dlevel.tscn

@@ -48,36 +48,21 @@ transform = Transform3D(1, 0, 0, 0, 0.25881907, 0.9659258, 0, -0.9659258, 0.2588
 shadow_enabled = true
 
 [node name="Player1" parent="." unique_id=68487004 instance=ExtResource("1_e2xum")]
-<<<<<<< HEAD
 transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, -1.0015082, 1, 0)
 
 [node name="Player2" parent="." unique_id=432105976 instance=ExtResource("1_e2xum")]
 transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 1.154851, 1, 0)
-=======
-transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, -1.1742709, 1, 0)
-
-[node name="Player2" parent="." unique_id=432105976 instance=ExtResource("1_e2xum")]
-transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 1.182826, 1, 0)
->>>>>>> main
 player_id = 2
 
 [node name="Path3DRope" parent="." unique_id=301387047 instance=ExtResource("2_jetiq")]
 curve = SubResource("Curve3D_epadm")
 attach_start_path = NodePath("../Player1")
 attach_end_path = NodePath("../Player2")
-<<<<<<< HEAD
 max_length = 4.0
 elastic_stiffness = 20.0
 haul_drag = 20.0
 reel_speed = 2.0
 number_of_segments = 16
-=======
-max_length = 6.0
-reel_speed = 2.0
-tension_start = 4.8
-snap_length = 10.0
-number_of_segments = 12
->>>>>>> main
 cable_thickness = 0.05
 fixed_start_point = false