On-screen look stick for first person

[hernan0078]

First person on a phone has the d-pad for walking and drag-anywhere for looking — but nothing on screen says the second one exists. A player who does not already know to drag cannot turn around.

This adds a thumbstick above A/B, drawn only while 1ST is driving.

It reuses your stick code rather than adding a parallel path. The touch stick writes into the same stick table gamepadaxis writes to, so it gets the rate-based response you already implemented: a held deflection keeps turning, with the squared curve. A drag-based stick would stop turning when the thumb hit the rim, which is the usual mistake. It centres on release.

Drag-anywhere is untouched underneath — the stick is an affordance for the thumb already over there, not a replacement for a flick with a spare finger.

Three rows come with it, gated to the 1ST rung so they are invisible everywhere else:

• LOOK STICK — hide it for controller players. Hiding also stops it claiming touches, or it would be an invisible control eating thumbs.
• LOOK SPEED — SLOW / NORMAL / FAST
• INVERT Y

Two design notes:

The preferences apply in a steer() layer around the three device inputs rather than inside lookBy. I put them in lookBy first and it broke your test asserting a 2π turn wraps to zero — correctly, since that is the primitive the rig drives and one full turn must stay one full turn whatever the sensitivity is set to.

ModSetting gains an optional default index. LOOK SPEED reads SLOW/NORMAL/FAST in that order but should start at NORMAL, and rung 1 was the only default available. Existing calls are unaffected.

Tested on a physical iPhone 17 Pro, and run against the engine test suite in my own tree, where the mod tier passes apart from a pushBattle failure that predates this branch.