integrate epd_case into lid module; simplify lid.scad and bottom.scad

- epd_case() now rendered inside lid() when SHOW_EPD_CASE=true, replacing the standalone ceiling plate
- epd_case assembly block removed from cpu_case top-level
- lid.scad calls lid() directly at Z=0; SHOW_EPD_CASE=true selects combined output
- bottom.scad explicitly sets SHOW_BATTERY=false and SHOW_EPD_CASE=false

bottom.scad

@@ -1,9 +1,11 @@
 include <cpu_case.scad>
 
-SHOW_BASE     = false;
 SHOW_BOARD    = false;
 SHOW_LID      = false;
+SHOW_BASE     = true;
 SHOW_PLUNGERS = false;
+SHOW_BATTERY  = false;
+SHOW_EPD_CASE = false;
 
 // Base is already floor-down, cavity-up — correct print orientation at origin
 base();

cpu_case.scad

@@ -291,6 +291,13 @@ module lid() {
             if (!SHOW_EPD_CASE)
                 translate([0, -WALL, FLANGE_H])
                     rounded_box(OUT_L, OUT_W, LID_T, CORNER_R);
+            else
+                translate([
+                            OUT_L/2 - _EPD_CASE_W/2,
+                            OUT_W - _EPD_CASE_D,
+                            LID_T
+            ])
+                epd_case();
 
             // Y- lip — same rounded_box profile clipped to the Y- wall zone so the
             // lip corners match the base exterior corners
@@ -349,12 +356,3 @@ if (SHOW_PLUNGERS)
     for (bcx = BTN_CX)
         translate([PCB_OX + bcx, OUT_W - WALL, PCB_Z + BTN_CZ])
             plunger();
-
-if (SHOW_EPD_CASE)
-    translate([
-        OUT_L/2 - _EPD_CASE_W/2,
-        OUT_W - EXPLODE - _EPD_CASE_D,
-        BASE_H
-    ])
-        epd_case();
-

lid.scad

@@ -2,10 +2,10 @@ include <cpu_case.scad>
 
 SHOW_BASE     = false;
 SHOW_BOARD    = false;
-SHOW_LID      = false;
+SHOW_BATTERY  = false;
 SHOW_PLUNGERS = false;
+SHOW_LID      = false;
+SHOW_EPD_CASE = true;
+EXPLODE       = 0;
 
-// Ceiling on build plate, flanges pointing up — matches the "print upside-down" note in cpu_case.scad
-translate([0, LID_Y_LEN, LID_H])
-    rotate([180, 0, 0])
-        lid();
+lid();