Address review feedback

- Remove unnecessary uint64_t cast on esp_timer_get_time() (already
  returns int64_t, always non-negative after boot)
- Fix next_schedule_in @param comment: now is only unused on ESP32,
  used for rollover tracking on other platforms
- Use fully-qualified friend declaration (::esphome::millis_64())

esphome/components/esp32/core.cpp

@@ -23,7 +23,7 @@ namespace esphome {
 
 void HOT yield() { vPortYield(); }
 uint32_t IRAM_ATTR HOT millis() { return (uint32_t) (esp_timer_get_time() / 1000ULL); }
-uint64_t HOT millis_64() { return static_cast<uint64_t>(esp_timer_get_time()) / 1000ULL; }
+uint64_t HOT millis_64() { return esp_timer_get_time() / 1000; }
 void HOT delay(uint32_t ms) { vTaskDelay(ms / portTICK_PERIOD_MS); }
 uint32_t IRAM_ATTR HOT micros() { return (uint32_t) esp_timer_get_time(); }
 void IRAM_ATTR HOT delayMicroseconds(uint32_t us) { delay_microseconds_safe(us); }

esphome/core/scheduler.h

@@ -121,7 +121,7 @@ class Scheduler {
   uint64_t millis_64() { return esphome::millis_64(); }
 
   // Calculate when the next scheduled item should run
-  // @param now Unused, kept for API compatibility
+  // @param now On ESP32, unused (native 64-bit); on other platforms, extended to 64-bit via rollover tracking
   // Returns the time in milliseconds until the next scheduled item, or nullopt if no items
   // This method performs cleanup of removed items before checking the schedule
   // IMPORTANT: This method should only be called from the main thread (loop task).
@@ -299,7 +299,7 @@ class Scheduler {
   // On non-ESP32 platforms, millis_64() HAL function delegates to this method
   // which tracks 32-bit millis() rollover using millis_major_ and last_millis_.
   // On ESP32, millis_64() uses esp_timer_get_time() directly.
-  friend uint64_t millis_64();
+  friend uint64_t ::esphome::millis_64();
   uint64_t millis_64_impl_(uint32_t now);
 #endif
   // Cleanup logically deleted items from the scheduler