[Docs] Update mobile controls pages for the shipped HUD layout

## **⚠️ Problem:**
Both mobile controls pages still describe the pre-#2642 HUD — a top-right camera control that no longer exists, a joystick locked to the left side, and screenshots of a layout that shipped over three weeks ago. Players follow instructions for buttons that aren't on screen and creators size their UI against a stale HUD, feeding the mobile "feels broken" perception behind `Playtime`; no drop-off number exists for these pages.

## **🏁 Scope:**
Bring `player/mobile-app/controls.md` and the two creator controls pages in line with the HUD shipped in #2642 — camera mode in Settings, free-roaming joystick, reworked Hide UI, portrait behavior — and recapture every controls screenshot. Out of scope: the safe-area page (already rewritten in #2639), `TouchScreenControls` API semantics, and the Creator Hub visual editor (#2671).

## **📝 Deliverables:**
- [ ] `player/mobile-app/controls.md` Camera section rewritten — mode is a Settings › Gameplay dropdown, greyed out when the scene locks it, absent outside worlds
- [ ] Player page movement + Hide UI corrected — joystick starts anywhere on screen, joypad sits inside the HUD rectangle, portrait hides both, Show UI restores chat
- [ ] `build-for-mobile/develop/input-on-mobile.md` and `sdk7/interactivity/touch-screen-controls.md` HUD references reconciled with the shipped layout
- [ ] Controls screenshots recaptured on a post-#2642 build — `.gitbook/assets/mobile-controls.png` and `creator/images/touch-controls/`
- [ ] PR opened against `decentraland/docs` and linked back here

## Notes
- Player page currently hedges the joystick long-press as "depending on app version" — confirm against the shipped build or cut it.
- Open question: does the player page mention Settings › Developer › Show Interactable Area, or stay creator-only?

## **🔗 References:**
- [decentraland/godot-explorer#2642](https://github.com/decentraland/godot-explorer/pull/2642) — the merged HUD + Social Panel redesign. Source of truth for every change these pages must absorb: shared safe-area rectangle via `hud_margins.tres`, camera dropdown, full-screen joystick, Hide UI rework, symmetric side margins.
- [decentraland/godot-explorer#2343](https://github.com/decentraland/godot-explorer/issues/2343) — iOS/Android HUD misalignment, closed by #2642. Explains why the old screenshots differ per platform.
- [decentraland/godot-explorer#2639](https://github.com/decentraland/godot-explorer/issues/2639) — the safe-area docs rewrite, already closed. Sets the terminology (`InteractableArea` / `DeviceSafeInset`) these pages must not contradict, and marks what is already covered.
- [decentraland/docs#122](https://github.com/decentraland/docs/pull/122) — merged 2026-08-13, authored the creator controls pages and the `creator/images/touch-controls/` screenshots. Those assets predate the shipped HUD.