feat(q5_max): add per-key tapping term with 50ms for home/end tap-dance

Define TAPPING_TERM (200ms default) and TAPPING_TERM_PER_KEY in config.h,
then implement get_tapping_term() to set a tight 50ms window for TD_HOME_END
so a single Home tap never accidentally resolves as End.

keyboards/keychron/q5_max/ansi_encoder/keymaps/via/config.h

@@ -16,3 +16,8 @@
 // Always resolve combo keycodes from BASE (layer 0) so the
 // COMM+DOT+SLSH fallback combo fires regardless of the active layer.
 #define COMBO_ONLY_FROM_LAYER 0
+
+// Default tapping term for mod-tap, layer-tap, and tap-dance keys.
+#define TAPPING_TERM 200
+// Allow per-key overrides via get_tapping_term() in keymap.c.
+#define TAPPING_TERM_PER_KEY

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

@@ -438,6 +438,15 @@ bool rgb_matrix_indicators_advanced_user(uint8_t led_min, uint8_t led_max) {
 }
 #endif // RGB_MATRIX_ENABLE
 
+uint16_t get_tapping_term(uint16_t keycode, keyrecord_t *record) {
+    switch (keycode) {
+        case TD(TD_HOME_END):
+            return 175;
+        default:
+            return TAPPING_TERM;
+    }
+}
+
 // Tap Dance definitions
 tap_dance_action_t tap_dance_actions[] = {
     // Tap once for Home, twice for End