feat(q5_max): map dip-switch to RGB effects (heatmap / solid white)

Replace the Win/Mac default-layer switch with an RGB effect toggle:
- Win side → solid white backlight
- Mac side → typing heatmap

Add a weak dip_switch_update_keymap() hook in q5_max.c to work around
factory_test.c already owning dip_switch_update_user().

keyboards/keychron/q5_max/ansi_encoder/keymaps/via/keymap.c

@@ -259,6 +259,27 @@ void keyboard_post_init_user(void) {
     set_unicode_input_mode(UNICODE_MODE_LINUX);
 }
 
+#ifdef DIP_SWITCH_ENABLE
+// dip_switch_update_user is claimed by factory_test.c; use the weak
+// dip_switch_update_keymap hook added in q5_max.c instead.
+void dip_switch_update_keymap(uint8_t index, bool active) {
+    if (index == 0) {
+        if (active) {
+            // "Win" side → solid white backlight
+            rgb_matrix_mode(RGB_MATRIX_SOLID_COLOR);
+            rgb_matrix_sethsv(HSV_WHITE);
+        } else {
+            // "Mac" side → heatmap effect.
+            // Restore hue+saturation before switching modes: the heatmap reads
+            // rgb_matrix_config.hsv.s directly for its color scale, so leaving
+            // saturation=0 (from HSV_WHITE) produces a white-only heatmap.
+            rgb_matrix_sethsv(0, 255, rgb_matrix_get_val());
+            rgb_matrix_mode(RGB_MATRIX_TYPING_HEATMAP);
+        }
+    }
+}
+#endif
+
 bool process_record_user(uint16_t keycode, keyrecord_t *record) {
     if (!process_record_keychron_common(keycode, record)) {
         return false;

keyboards/keychron/q5_max/q5_max.c

@@ -29,11 +29,16 @@
 
 
 #ifdef DIP_SWITCH_ENABLE
+// Weak hook — override in keymap.c to handle dip-switch events
+// without conflicting with factory_test.c's dip_switch_update_user.
+__attribute__((weak)) void dip_switch_update_keymap(uint8_t index, bool active) {}
+
 bool dip_switch_update_kb(uint8_t index, bool active) {
-    if (index == 0) {
+    // if (index == 0) {
-        default_layer_set(1UL << (active ? 2 : 0));
+    //     default_layer_set(1UL << (active ? 2 : 0));
-    }
+    // }
     dip_switch_update_user(index, active);
+    dip_switch_update_keymap(index, active);
 
     return true;
 }