Derive FPC_NOTCH_W and FPC_SLOT_W from epd_case geometry

Values now match the Z- face opening of epd_case: FPC_NOTCH_W=17.5
(= _fpc_xw, cable + 2×2.5 mm clearance) and FPC_SLOT_W=4.1
(≈ arc Y-extent at z=0 with epd_case defaults).

cpu_case.scad

@@ -28,11 +28,15 @@ FLANGE_W    =  FLANGE_H * tan(30);   // flange width — 30° from vertical (60
 SLIDE_CLEAR =  0.40;  // clearance between flange/rib and groove/channel on all mating faces (0.4 mm suits typical FDM tolerances)
 
 // ---- Y- edge: FPC connector — notch in lid Y+ stop rib ----
+// FPC_NOTCH_W and FPC_SLOT_W match the Z- face opening of epd_case:
+//   _fpc_xw = 12.5 + 5.0 = 17.5 mm (cable + 2.5 mm clearance per side)
+//   slot Y-extent at z=0: sqrt(_fpc_ro² − (FPC_BEND_R−WALL)²) ≈ 4.1 mm
+//   with epd_case defaults: bend_r=4, wall=2, fpc_t=0.3, tol=0.3 → _fpc_ro=4.6
 FPC_CX      =  50.0;   // PCB-relative case_x centre
-FPC_NOTCH_W =  20.0;   // notch width for cable routing clearance
+FPC_NOTCH_W =  17.5;   // = _fpc_xw in epd_case (cable 12.5 + 2×2.5 mm clearance)
 FPC_U_T     = LID_T;   // U-rib arm and bar thickness
 FPC_U_DEPTH =  20.0;   // how far Y- the U arms extend into the lid interior
-FPC_SLOT_W  =   3.0;   // Y depth of ceiling slot the cable exits through
+FPC_SLOT_W  =   4.1;   // ≈ sqrt(_fpc_ro²−(FPC_BEND_R−WALL)²) at epd_case z=0
 
 /* [Cutout Positions — from STL geometry, PCB-origin-relative] */