epd_case: widen display window 0.3mm per side

Adds WIN_W_EXTRA=0.3 so the window cutout is 0.6mm wider than ACT_W
without touching the display pocket dimensions.

epd_case.scad

@@ -21,12 +21,12 @@ module epd_case() {
     // Active area window: straight portion + chamfered top edges
     // Extends 0.01 mm into the display cavity to avoid a coplanar face with the mockup
     translate([epd_win_x, epd_win_y, WALL + DISP_T - 0.01])
-      cube([ACT_W, ACT_D, LIP - CHAM + 0.02]);
+      cube([epd_win_w, ACT_D, LIP - CHAM + 0.02]);
     hull() {
       translate([epd_win_x, epd_win_y, epd_case_h - CHAM])
-        cube([ACT_W, ACT_D, 0.01]);
+        cube([epd_win_w, ACT_D, 0.01]);
       translate([epd_win_x - _cham_xy, epd_win_y - _cham_xy, epd_case_h])
-        cube([ACT_W + 2*_cham_xy, ACT_D + 2*_cham_xy, 0.01]);
+        cube([epd_win_w + 2*_cham_xy, ACT_D + 2*_cham_xy, 0.01]);
     }
 
     // FPC cable slot — quarter-cylinder swept volume of cable arc from horizontal to vertical.

params.scad

@@ -37,7 +37,9 @@ _fpc_ro    = FPC_BEND_R + 0.30 + TOL;
 _bend_my   = BEZEL_Y + DISP_D + sqrt(_fpc_ro*_fpc_ro - (FPC_BEND_R - WALL)*(FPC_BEND_R - WALL));
 epd_case_d = max(epd_cav_d + WALL + BEZEL_Y, _bend_my + WALL) + BEZEL_YP;
 _cham_xy   = CHAM * tan(CHAM_ANGLE);
-epd_win_x  = WALL + TOL + (DISP_W - ACT_W) / 2;
+WIN_W_EXTRA = 0.3;  // extra clearance added to each side of window vs. active area
+epd_win_w  = ACT_W + 2 * WIN_W_EXTRA;
+epd_win_x  = WALL + TOL + (DISP_W - ACT_W) / 2 - WIN_W_EXTRA;
 epd_win_y  = 3.30 + BEZEL_Y;
 
 /* [Board Dimensions — EE04] */