Controller board: ESP32 + 2x StepStick carrier (v0.4), FluidNC config

- KiCad project generated by pcb/tools (design, route, schematic, fab outputs).
- v0.4 fixes the v0.3 review findings: low-dropout 3.3 V regulator, OR'd 5 V
  supply, polyfuse, USB ESD protection, input clamps, ceramic decoupling at the
  drivers, A4988/DRV8825 jumper, ground stitching. DRC/ERC clean.
- v0.3 (as ordered) kept in pcb/archive/v0.3.
- FluidNC config.yaml for the board; rho hard limit on.

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

pcb/tools/place_new.py

@@ -0,0 +1,67 @@
+"""Find free spots for parts added in a revision: a spiral search around each part's
+preferred position (from design.py), trying 4 rotations, keeping courtyards apart,
+inside the board and out of the antenna keep-out. Prints the positions to paste into design.py."""
+import math
+import sys
+import os
+
+sys.path.insert(0, os.path.dirname(__file__))
+import design as D
+from board import build
+
+GAP = 0.25                    # min gap between courtyards, mm
+KEEPOUT = (18.75, 56.9, 67.25, D.BOARD_H)   # ESP32 antenna
+EDGE = 0.6
+
+
+def overlaps(a, b, gap=GAP):
+    return min(a[2], b[2]) - max(a[0], b[0]) > -gap and min(a[3], b[3]) - max(a[1], b[1]) > -gap
+
+
+def legal(part, fixed):
+    for r in part.court_rects():
+        if r[0] < EDGE or r[1] < EDGE or r[2] > D.BOARD_W - EDGE or r[3] > D.BOARD_H - EDGE:
+            return False
+        if overlaps(r, KEEPOUT, 0):
+            return False
+        if any(overlaps(r, f) for f in fixed):
+            return False
+    return True
+
+
+def place(refs, parts):
+    fixed = [r for ref, p in parts.items() if ref not in refs for r in p.court_rects()]
+    out = {}
+    for ref in refs:
+        p = parts[ref]
+        x0, y0, rot0 = p.x, p.y, p.rot
+        best = None
+        for step in range(0, 80):          # radius in 0.25 mm steps, up to 20 mm
+            rad = step * 0.25
+            n = max(1, int(2 * math.pi * rad / 0.25))
+            for i in range(n):
+                a = 2 * math.pi * i / n
+                x, y = round(x0 + rad * math.cos(a), 2), round(y0 + rad * math.sin(a), 2)
+                for rot in (rot0, (rot0 + 90) % 360, (rot0 + 180) % 360, (rot0 + 270) % 360):
+                    p.x, p.y, p.rot = x, y, rot
+                    if legal(p, fixed):
+                        best = (x, y, rot, rad)
+                        break
+                if best:
+                    break
+            if best:
+                break
+        if not best:
+            print(f'{ref}: no spot within 20 mm')
+            p.x, p.y, p.rot = x0, y0, rot0
+            continue
+        p.x, p.y, p.rot = best[:3]
+        fixed += p.court_rects()
+        out[ref] = best
+        print(f'{ref}: ({best[0]}, {best[1]}) rot {best[2]}  moved {best[3]:.2f} mm from preferred')
+    return out
+
+
+if __name__ == '__main__':
+    parts = build()
+    place(sys.argv[1:], parts)