Render air bubbles with sprites

[Purdze]

Summary

• Register hud/air, hud/air_bursting, hud/air_empty sprites in the atlas
• Replace the placeholder rect-based air bubbles with sprite rendering that matches vanilla's renderAirBubbles logic (full, bursting, empty states)
• Show the bubble row whenever the player is submerged or air is below max (previously only shown when air was below max)
• Pass eyes_in_water through to build_hud

Test plan

• On land with full air, no bubble row shown
• Submerge head in water, full 10 bubbles appear
• Hold underwater, bubbles deplete right-to-left with leading bubble flashing the bursting sprite
• Surface with partial air, bubbles refill (no bursting while above water), row disappears at full