Settle the numpad layout: 25 keys, one encoder

Six by five. Arrows on the outer column, PgUp/PgDn beside them, no Num key.
The scroll wheel is dropped - no good physical implementation - which also
removes the pointing-device path from the firmware entirely, frees a USB
endpoint, and retires the detentless-EC11 sourcing risk. The freed 2u at the
top takes a single volume encoder with room for a full-size knob.

BOM: diodes and sockets 26 -> 25, encoders 2 -> 1.

Co-Authored-By: Claude Opus 5 <[email protected]>

README.md

@@ -12,7 +12,15 @@ Status: **design**. No boards ordered, no firmware written.
 | Board | Qty | Keys | Carries |
 |---|---|---|---|
 | `hardware/half` | 2 (mirrored) | TBD — layout not designed | MCU, matrix, USB-C, SBU split link |
-| `hardware/numpad` | 1 | 26 (17 numpad + 9 nav) | MCU, matrix, 2 encoders, **CH334R hub**, 3 downstream ports |
+| `hardware/numpad` | 1 | 25 (16 numpad + 9 nav) | MCU, matrix, 1 encoder, **CH334R hub**, 3 downstream ports |
+
+**Numpad layout is settled** — see `docs/numpad-layout.svg`. Six columns by five
+rows, ~114 × 95 mm. Arrows take the **outer** left column on the principle that
+the most-used keys go furthest out, PgUp/PgDn sit beside them, and Del/Home/End
+fill the rest of the two nav columns. **No Num key** — the firmware resolves
+keypad vs number-row at press time, so the pad never needed one. The 2u that
+frees up at the top holds the single volume encoder, which means a full-size
+knob fits rather than two cramped ones colliding at 19.05 mm centres.
 
 Cabling:
 
@@ -189,10 +197,19 @@ Plan is belt-and-braces:
 Only eleven keys need this (1–9, 0, `.`). `KP_SLASH`/`ASTERISK`/`MINUS`/`PLUS`/
 `ENTER` mean the same thing either way.
 
-**Encoders:** volume wants a **detented** EC11; scroll wants a **detentless** one,
-because hi-res scrolling (`POINTING_DEVICE_HIRES_SCROLL_ENABLE`, resolution
-multiplier, 1/120 tick) fights physical detents. Confirm the detentless SKU from
-the datasheet — vendor descriptions are unreliable.
+**One encoder, volume only.** The scroll wheel was dropped — no good physical
+implementation. That removes more than it looks like:
+
+- No `POINTING_DEVICE_ENABLE`, no `MOUSEKEY_ENABLE`, no hi-res scroll resolution
+  multiplier. **The numpad stops enumerating as a mouse entirely** — it's a
+  keyboard plus consumer control and nothing else.
+- One fewer USB endpoint, which matters because the L103's USBFS has eight and
+  QMK's composite device was going to be tight against that.
+- The detentless-EC11 sourcing risk is gone. A stock EC11 is detented, which is
+  exactly what volume wants, so `C2991196` is simply correct with nothing to
+  verify.
+
+Rules file is now just `ENCODER_ENABLE` + `EXTRAKEY_ENABLE`.
 
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