2026 hardware: add main-pcb-2026-11-13/

The Teensy 3.6 carrier board mounted inside the robot body (Teensy
peeks through the top-body hole). Contents:

- PCB_test_2026-11-13.json : EasyEDA PCB source (editor v6.5.61).
- OBJ_test.obj + .mtl      : EasyEDA 3D OBJ export (slab + holes only).
- top.png, bottom.png      : EasyEDA renders of each side; bottom.png
                             is the authoritative source for the
                             JP1-JP7 silkscreen numbering.
- 20190524_234512.jpg      : photo of the populated bottom side.
- 20190524_234518.jpg      : photo of the top side, powered on.
- main-pcb.scad            : parametric OpenSCAD reconstruction. Real
                             board outline, 4 M3 holes, and every major
                             component (Teensy 3.6, nRF24L01+, GY-521
                             IMU, 7805, ZENER, JP7 battery JST, six
                             JST-PH 2mm servo headers JP1-JP6, POWER
                             LED + 510R resistor, "Hexapod v1" silk) on
                             the correct side of the board. Placements
                             are the pad-group centres pulled from the
                             EasyEDA JSON, not eyeballed.
- README.md                : explains the files, the EasyEDA format and
                             unit conversion, which side each part is
                             on, and an authoritative placement table.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

2026-current/hardware/main-pcb-2026-11-13/OBJ_test.mtl

@@ -0,0 +1,5 @@
+newmtl mtl1
+Ka 0.62 0.62 0.36
+Kd 0.62 0.62 0.36
+Ks 0.00 0.00 0.00
+endmtl