Fold LEGACY into the generation folders

The LEGACY copies of HexapodRobot, Hexapod_NEW, Hexapod_Teensy and the old remote sketch were identical to the imported repos and are removed. The old Nextion design moves to 2019-teensy-nrf24/remote-nextion/, the 2019 remote case files to 2019-teensy-nrf24/remote-case/. Paths in CLAUDE.md, READMEs, remote/ comments, sim/build.ps1, the Unity DLL message and .vscode/settings.json now point to the new places. robot/ is not touched (its CLAUDE.md asks to check with the owner first).

2026-current/Hexapod_Simulation_Unity/Assets/HexapodSim/HexapodSimNative.cs

@@ -112,7 +112,7 @@ namespace HexapodSim
         {
             if (!File.Exists(dllPath))
                 throw new FileNotFoundException(
-                    "Simulation DLL not found. Build it first: run .\\sim\\build.ps1 from the repo root in PowerShell.",
+                    "Simulation DLL not found. Build it first: run .\\sim\\build.ps1 from the 2026-current folder in PowerShell.",
                     dllPath);
 
             var n = new HexapodSimNative();