feat: HUD

- add HUD class with font initialization
- add status bars for doors and zombie hp
- add ECTS balance and generation rate display
- add game timer

src/hud.py

@@ -21,3 +21,27 @@ def _format_time(total_seconds):
     mins = total_seconds // 60
     secs = total_seconds % 60
     return f"TIME {mins:02}:{secs:02}"
+
+
+class HUD:
+    def __init__(self):
+        self.font = pygame.font.SysFont(HUD_FONT, HUD_FONT_SIZE, bold=HUD_FONT_BOLD)
+
+    def draw(self, screen, door, zombie, ects, total_time):
+        # --- DOOR HP ---
+        _draw_status_bar(screen, HUD_BAR_X, HUD_Y_DOOR, door.current_hp, COLOR_HP_BAR_GREEN)
+        # -5 px, small off-set to align the text better with hp bar
+        screen.blit(self.font.render("DOOR HP ", True, COLOR_HUD_TEXT), (HUD_X_OFFSET, HUD_Y_DOOR - 5))
+
+        # --- ZOMBIE HP ---
+        if zombie:
+            _draw_status_bar(screen, HUD_BAR_X, HUD_Y_ZOMBIE, zombie.current_hp, zombie.max_hp, COLOR_HP_BAR_RED)
+            screen.blit(self.font.render("Zombie HP:", True, COLOR_HUD_TEXT), (HUD_X_OFFSET, HUD_Y_ZOMBIE - 5))
+
+        # --- ECTS ---
+        ects_info = f"ECTS: {ects.ects_balance} ({ects.ects_per_second}/s)"
+        screen.blit(self.font.render(ects_info, True, COLOR_HUD_TEXT), (HUD_X_OFFSET, HUD_Y_ECTS))
+
+        # --- TIME ---
+        time_str = _format_time(total_time)
+        screen.blit(self.font.render(time_str, True, COLOR_HUD_TEXT), (screen.get_width() - 150, HUD_Y_DOOR - 5))