Adds a nitrous boost on top of master’s single chase camera (independent of the multi-camera / CameraHud work on camera-switch). The tank drains while boosting, recharges while drifting, and is reflected in HUD + particles + audio + camera shake.

What’s included

Gameplay & input

• Keyboard X and gamepad RB to hold boost (unchanged from base NOS).
• NOS HUD “X” button: hold (pointer or Space/Enter when focused) to boost, same as the key—uses Controls.nosUiHeld so it stays in sync with the sim.
• Window blur releases UI boost so you don’t get stuck “on” after alt-tab.

HUD

• White key-style control + NOS label.
• Live “% left” (0–100) with a tank bar; button visually dims at 0% (aria-disabled when empty).

Other

• Vehicle: cap, drive mult, body/wheel lift, tank + intensity, drift recharge.
• Camera: NOS shake on chase Camera.update(..., nosIntensity).
• FX: extra smoke when boosting, red NOS taillight trails, whoosh on boost start.
• Out of scope here: CameraHud, C to cycle camera, hood/third/eagle stack (see camera-switch).

How to test

1. Run the static server, load this branch.
2. X or RB: hold = boost, HUD % and bar drop, effects + sound.
3. Click/touch and hold the white X in the bottom-left: same as holding X.
4. Drift: tank refills per existing tuning.
5. At 0%: bar empty, button dimmed; no boost until recharged.

Reviewer note

Merges cleanly as a feature branch from master. If you later merge with camera-switch, expect resolve in Controls.js, Camera.js, Vehicle.js, and main.js for combined camera + NOS wiring.