Add HEER S1 macropad (#26373)

* Add HEER S1 macropad

* Address review feedback for HEER S1

- readme: add product image, correct maintainer link and availability URL
- config.h: drop OLED_DISPLAY_ADDRESS, already the driver default
- keyboard.json: drop the i2c block, which only feeds split transport
- move the OLED to heer_s1.c as oled_task_kb
- default keymap reduced to keymaps[] and encoder_map[]

The default keymap also configured GP16/GP17 as GPIO inputs at boot. Those are
the OLED's I2C SDA/SCL lines, so it tore down the display bus on every start.
The encoder switches are on GP2/GP14. Removed along with the rest of the code.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Update keyboards/heer_s1/keymaps/default/keymap.c

Co-authored-by: Joel Challis <git@zvecr.com>

* Update keyboards/heer_s1/keymaps/default/keymap.c

Co-authored-by: Joel Challis <git@zvecr.com>

* Update keyboards/heer_s1/keymaps/default/keymap.c

Co-authored-by: Joel Challis <git@zvecr.com>

* Update keyboards/heer_s1/keymaps/default/keymap.c

Co-authored-by: Joel Challis <git@zvecr.com>

* Update keyboards/heer_s1/keyboard.json

Co-authored-by: Joel Challis <git@zvecr.com>

* Update keyboards/heer_s1/readme.md

Co-authored-by: Joel Challis <git@zvecr.com>

* Update keyboards/heer_s1/keymaps/default/keymap.c

Co-authored-by: Joel Challis <git@zvecr.com>

* Update keyboards/heer_s1/keyboard.json

Co-authored-by: Joel Challis <git@zvecr.com>

* Update keyboards/heer_s1/keyboard.json

Co-authored-by: Joel Challis <git@zvecr.com>

* Fix duplicated enumerators in default keymap

The suggested enum replacement was applied alongside the original entries
rather than in place of them, leaving L_BASE, L_MEDIA and L_EDIT declared
twice.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Update keyboards/heer_s1/readme.md

Co-authored-by: Joel Challis <git@zvecr.com>

* Update keyboards/heer_s1/keyboard.json

Co-authored-by: Joel Challis <git@zvecr.com>

---------

Co-authored-by: HEER <heerelectronix@gmail.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
Co-authored-by: Joel Challis <git@zvecr.com>

keyboards/heer_s1/keymaps/default/keymap.c

@@ -0,0 +1,56 @@
+// Copyright 2026 Heer (@heer)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include QMK_KEYBOARD_H
+
+enum layers {
+    L_BASE,
+    L_MEDIA,
+    L_EDIT,
+    L_SYS,
+};
+
+// The bottom-right key advances to the next layer and wraps, so all four are
+// reachable using nothing but standard keycodes.
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+    [L_BASE] = LAYOUT(
+        TO(L_MEDIA), TO(L_BASE),
+        KC_1,    KC_2,    KC_3,    KC_4,
+        KC_5,    KC_6,    KC_7,    KC_8,
+        KC_9,    KC_0,    KC_MINS, KC_EQL,
+        KC_BSPC, KC_ENT,  KC_ESC,  TO(L_MEDIA)
+    ),
+
+    [L_MEDIA] = LAYOUT(
+        TO(L_EDIT), TO(L_BASE),
+        KC_MPLY, KC_MSTP, KC_MPRV, KC_MNXT,
+        KC_VOLD, KC_VOLU, KC_MUTE, _______,
+        KC_BRID, KC_BRIU, _______, _______,
+        _______, _______, _______, TO(L_EDIT)
+    ),
+
+    [L_EDIT] = LAYOUT(
+        TO(L_SYS), TO(L_BASE),
+        LCTL(KC_Z), LCTL(KC_X), LCTL(KC_C), LCTL(KC_V),
+        LCTL(KC_A), LCTL(KC_S), LCTL(KC_F), LCTL(KC_H),
+        LCTL(KC_N), LCTL(KC_W), LCTL(KC_T), LCTL(KC_P),
+        KC_DEL,     KC_HOME,    KC_END,     TO(L_SYS)
+    ),
+
+    [L_SYS] = LAYOUT(
+        TO(L_BASE), TO(L_BASE),
+        KC_F1,   KC_F2,   KC_F3,   KC_F4,
+        KC_F5,   KC_F6,   KC_F7,   KC_F8,
+        KC_F9,   KC_F10,  KC_F11,  KC_F12,
+        KC_PSCR, KC_SCRL, KC_PAUS, TO(L_BASE)
+    ),
+};
+
+#if defined(ENCODER_MAP_ENABLE)
+const uint16_t PROGMEM encoder_map[][NUM_ENCODERS][NUM_DIRECTIONS] = {
+    [L_BASE]  = { ENCODER_CCW_CW(KC_VOLD, KC_VOLU),       ENCODER_CCW_CW(KC_LEFT, KC_RGHT) },
+    [L_MEDIA] = { ENCODER_CCW_CW(KC_MPRV, KC_MNXT),       ENCODER_CCW_CW(KC_BRID, KC_BRIU) },
+    [L_EDIT]  = { ENCODER_CCW_CW(LCTL(KC_Z), LCTL(KC_Y)), ENCODER_CCW_CW(KC_UP,   KC_DOWN) },
+    [L_SYS]   = { ENCODER_CCW_CW(KC_F11,  KC_F12),        ENCODER_CCW_CW(KC_PGDN, KC_PGUP) },
+};
+#endif