feat(case): add a reset button hole in the back wall

Momentary switch wired to the board's EN/GND, mounted past the µSD so
it's never hit while typing. BOOT is omitted on purpose: on the S3,
auto-download makes it recovery-only. Positions are << MEASURE >>
placeholders — a custom carrier PCB will re-fix them later.

hardware/case/README.md

@@ -114,6 +114,13 @@ from below — far easier than fishing screws inside a shell.
 - The **DESPI-C579 breakout** sits in the cavity on the **left**, right under the
   FPC exit; short SPI jumpers (MOSI/SCLK/CS/DC/RST/BUSY + 3V3/GND) run across to
   the ESP32. Keep that left channel clear.
+- A **reset button** — a small momentary switch, soldered to the board's **EN**
+  and **GND** header pins — mounts through a hole in the back wall, out past the
+  µSD slot so it's never hit while typing (`rst_*` params, `<< MEASURE >>`). This
+  is our own switch, not the DevKitC's on-board buttons: those are top-actuated
+  and buried once the board lies flat. **BOOT is deliberately omitted** — on the
+  S3, auto-download (UART-bridge DTR/RTS or the native USB-Serial-JTAG) makes it
+  recovery-only, not worth a fat-fingerable button on a writing appliance.
 - The baseplate screws **up into 4 corner posts** in the shell.
 - A **cable relief** notch at the back lets the keyboard's USB-C cable exit and
   route around to the front.
@@ -146,7 +153,8 @@ Or inspect each half alone — `plan_up` (the deck/lid, shown from below) and
 - **`Hb` (back height) → deck angle.** 18–22° is typewriter-shallow; raise `Hb`
   toward ~28–35° if the screen reads too edge-on when you're sitting close.
 - **`<< MEASURE >>` items:** `esp_holes`, `brk_holes`, `port_x`, `port_z`,
-  `active_off_x/y` (the panel's active area sits off-centre from the glass).
+  `rst_x`/`rst_z`/`rst_d` (reset button), `active_off_x/y` (the panel's active
+  area sits off-centre from the glass).
 
 ## Print notes
 
@@ -189,7 +197,9 @@ name.
 
 - [ ] Confirm the GDEY0579T93 active-area **offset** (FPC confirmed on the left
       edge); adjust `active_off_x/y`.
-- [ ] Real ESP32-S3-DevKitC-1 mounting-hole + port coordinates.
+- [ ] Real board mounting-hole + port coordinates. **A custom carrier PCB is
+      planned** — when it lands, re-fix `esp_holes`, `port_x/z`, and the reset
+      `rst_*` to the PCB (and decide there whether to expose BOOT as a test pad).
 - [ ] Optional **hinged lid** over the deck (portable-typewriter-case echo,
       protects the glass in a bag) — `docs/hardware.md` calls for one; not yet
       modelled.

hardware/case/typoena-case.scad

@@ -86,6 +86,18 @@ sd_w     = 12;   sd_h   = 2.4;               // microSD slot
 // X positions of the three openings along the back << MEASURE to your board >>
 port_x   = [W/2 - 15, W/2, W/2 + 17];        // usb-c (kbd), usb-c (power), µSD
 
+// ---- reset button (momentary wired to EN/GND) -----------------------------
+// Our OWN switch, soldered to the board's EN + GND header pins — NOT the
+// DevKitC's on-board buttons (top-actuated and buried once the board lies flat
+// on its standoffs). It sits on the back wall, out past the µSD, so it's never
+// hit while typing. BOOT is left off on purpose: on the S3, auto-download
+// (UART-bridge DTR/RTS or the native USB-Serial-JTAG) makes it recovery-only —
+// not worth a fat-fingerable button on a writing appliance.
+rst_btn  = true;             // set false to omit the reset hole entirely
+rst_d    = 7.2;              // through-hole Ø for the switch barrel   << MEASURE >>
+rst_x    = W/2 + 40;         // X along the back wall (past the µSD @ +17)  << MEASURE >>
+rst_z    = 12;               // centre height off the desk             << MEASURE >>
+
 // ---- baseplate / chassis --------------------------------------------------
 bp_t       = 2.6;  // baseplate thickness
 bp_gap     = 0.5;  // clearance so it drops into the shell
@@ -202,6 +214,13 @@ module port_cuts() {
     }
 }
 
+// reset switch mounting hole through the back wall (y = D)
+module reset_cut() {
+    if (rst_btn)
+        translate([rst_x, D-wall-1, rst_z])
+            rotate([-90,0,0]) cylinder(h=wall+2, r=rst_d/2);
+}
+
 // engraved nameplate on the DECK, in the band between the front edge and the
 // screen — faces the user as they write. Sits flat on the reclined deck.
 module nameplate() {
@@ -221,6 +240,7 @@ module case_body() {
         }
         screen_cuts();
         port_cuts();
+        reset_cut();
         nameplate();                 // engrave (comment out for a blank face)
     }
 }