Robot: Teensy 3.6 with the old robot's servo wiring and calibration

- LEGACY/Hexapod_Teensy/: old robot sketch (reference only).
- platformio.ini: robot env targets teensy36 (owner-confirmed board).
- Config.h: per-servo SERVOS table (pin, pulse at 0 deg, signed
  us/deg, pulse limits) built from the old sketch's pins, ranges, trims
  and the old Unity servo directions. Rear-left/front-left coxa offsets
  set to 0: the owner re-horns those two servos (the old +-90 left them
  at the end of travel; the sim showed them clamping).
- ServoDriver: 18 servos on hardware PWM (50 Hz, 16-bit); the Teensy 3.6
  Servo library stops at 12.
- Radio on CE 39 / CSN 15 with SPI SCK on pin 14.
- sim: analogWrite/PWM shims, pulses decoded through SERVOS (API v6).
- Docs: CLAUDE.md, READMEs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-current/sim/HexapodSimApi.h

@@ -18,7 +18,7 @@
 #endif
 
 // Bump whenever a signature or struct below changes; the C# side checks it.
-#define HXSIM_API_VERSION 5
+#define HXSIM_API_VERSION 6
 
 #define HXSIM_NUM_LEGS 6
 
@@ -34,8 +34,6 @@ typedef struct {
   float femur_min_deg, femur_max_deg;
   float tibia_min_deg, tibia_max_deg;
   float control_hz;
-  int32_t servo_us_at_0deg;
-  int32_t servo_us_per_deg;
   float leg_clearance_mm;    // LEG_CLEARANCE_MM: minimum gap between neighbouring legs' segments
   float stance_height_range_mm;   // CmdPacket.body_height +-1000 moves the height by this much
 } HxGeometry;
@@ -81,7 +79,7 @@ HXSIM_API void    hxsim_serial_input(const char* bytes, int32_t len);    // TEST
 // Outputs
 HXSIM_API int32_t hxsim_serial_output(char* out, int32_t cap);           // drains robot Serial prints
 HXSIM_API void    hxsim_get_servos(int32_t* us_18, int32_t* attached_18, uint32_t* writes_18);
-HXSIM_API void    hxsim_get_joints_deg(float* deg_18);   // servo pulses decoded with Config.h constants
+HXSIM_API void    hxsim_get_joints_deg(float* deg_18);   // servo pulses decoded through Config.h's per-servo SERVOS table
 HXSIM_API void    hxsim_get_feet_mm(float* xyz_18);      // forward kinematics of those angles, body frame
 HXSIM_API void    hxsim_get_status(HxStatus* out);
 // Kinematic body (SimBody.cpp): the body rests on the support plane of its