The owner reported 「琳琅诗怀雅的2技能的香槟会掉血，会被治疗」. Allies always draw an HP bar (render/units.js
_updateHud), so the bomb's every HP change showed. PRTS 香槟炸弹 (实体类型 装置, 1000 HP) says no HP bar is shown even
below full HP; nothing there makes it invulnerable or unhealable. Its bar is now hidden at any HP (NO_HP_BAR). Its HP,
the damage it takes (活性源石 hurts what stands on it — 70 true damage a second) and healing are left as they are: no
invulnerability added; whether it should be unhealable is the owner's decision (no written source says so).
Tests: test/render/champagne-hpbar.test.js (new, 2: no bar at full HP, hurt or healed; another summon keeps its bar)
2/2; render/unitview 35/35.
