Gamepad plugin: on-screen touch controls, reported as a gamepad - #1799

A new package, @melonjs/gamepad-plugin, built from the plugin template
and following the in-repo plugins. It draws sticks and buttons and puts
a virtual pad in a gamepad slot (input.addVirtualGamepad), so a game's
bindGamepad bindings answer to the touch controls as to a real pad.

- one or two analog sticks with a deadzone; the left one presses the
  D-pad in 8 directions. Fixed or floating (centered where the thumb
  lands). Keys can be pressed instead, for keyboard-only games
- any number of buttons, FACE_1, FACE_2... by default or a key; a game
  can relabel, dim or hide them at run time
- each finger followed by its own pointer id from DOM pointer events,
  caught in the capture phase on the canvas's parent: a touch starting
  on the controls never reaches the engine or the game, and a stick
  keeps its finger when the thumb drifts off its base
- drawn after the stage, over every camera and every renderable,
  whatever their z, and so never inside a minimap; nothing to load,
  only the renderer's shapes; kept across stage changes
- `enabled` (device.touch by default) and `visible`; hidden while a
  real pad is in use (hideOnGamepad), back when it is unplugged or the
  screen is touched
- input.vibrateGamepad vibrates the phone through navigator.vibrate
- the minimum engine version comes from peerDependencies (>= 20.12.0,
  the release with addVirtualGamepad)

33 browser tests on the Canvas renderer, including that touches are
kept from the game and the controls are drawn over a full-screen
overlay; checked by hand on WebGL. Also: README, CHANGELOG, the API
docs entry, the melonjs-input skill (with symptom entries), CI test
and publish wiring, and the root README plugin list.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01JnzwA4xBNBw7cEZzG1bUru

`pnpm -F @melonjs/gamepad-plugin visual` serves visual/, a page with the
controls over a small scene, to try on a desktop or a phone (Vite serves
it on the network too). Not part of the published package.

- a dot the left stick moves (analog through LX/LY, digital through the
  D-pad), bound as a game binds a real pad
- a readout of the plugin's state and of what the engine receives: the
  axes on GAMEPAD_UPDATE, the actions held, the active slot, the real
  pads, and how many taps reached the game (a tap off the controls
  leaves a ring)
- toggles for enabled, two sticks, floating, hide on pad, dim / hide /
  relabel a button, a shade at a very high z, a minimap camera, phone
  vibration, and the renderer (?renderer=canvas|webgl|webgpu)

Checked in headless Chromium with real touch events on Canvas and WebGL:
two fingers on the stick and A at once reach the engine, the game gets
none of those touches but gets a tap in the open, the controls stay over
the shade, and the minimap draws the world without them.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01JnzwA4xBNBw7cEZzG1bUru

So it can pick its renderer where only the address hash reaches the page.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01JnzwA4xBNBw7cEZzG1bUru

Plugin
- touches are placed against this application's canvas from clientX/Y,
  so they land right on a scrolled page (globalToLocal takes page
  coordinates) and on a page with several applications
- hidden for a real pad again when the player goes back to it after
  touching the screen: the pads are watched each frame while one is
  connected, not only on GAMEPAD_CONNECTED
- the version, an initialized app and a free slot are checked before
  anything is hooked; a second set of controls on a slot throws even
  while switched off
- `ready` checks isInitialized and the viewport (a destroyed app keeps
  both), instead of a guard that was always true
- alpha and deadzone clamped with math.clamp: Canvas ignored an alpha
  above 1 when opacity was over 0.5
- a label keeps one Text, resized with setFont on layout and relabel
- a new vibration effect stops the one still running
- the control classes are exported as types; trimmed comments, a split
  CHANGELOG, README rows; the test page lets #hash win over ?renderer=

Engine
- one virtual pad cannot go in two slots; @throws lists the RangeError
- the connect listeners reuse hasGamepadApi(); reworded comments and
  CHANGELOG entries (a one-sided stick also stuck when it came back to
  exactly 0)
- tests: a negative-side stick back to 0, a keyboard key and a pad on
  one action, a remapped pad unplugged mid-press next to a virtual pad

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01JnzwA4xBNBw7cEZzG1bUru

…he README

As the debug plugin's README: the banner and badges under the title, and
a screenshot of the controls (a stick held and leaning, A pressed), taken
from the visual test page and shipped in the package.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01JnzwA4xBNBw7cEZzG1bUru

addVirtualGamepad, removeVirtualGamepad and VirtualGamepad stay in
input/gamepad.ts but are @ignore @internal: out of the docs and the
published types, there for the gamepad plugin only. The plugin declares
the two calls itself and reaches them through one cast. Their changelog
entry and skill paragraph go; the two gamepad fixes stay.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01JnzwA4xBNBw7cEZzG1bUru

In the API docs home page, llms.txt, and the melonjs, melonjs-plugins
(with its own section and trigger words) and AGENTS skills.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01JnzwA4xBNBw7cEZzG1bUru

…on-ao5snz

# Conflicts:
#	packages/melonjs/CHANGELOG.md