fix: restored p5.js keyword highlighting for CM6 #3868

[parthjadhao01]

Issue:

Fixes #3868

This PR restores p5.js-specific syntax highlighting in the CodeMirror v6 branch. In the CM5 editor, p5 functions (like setup, draw, background) appeared bold blue and p5 constants/variables (like PI, mouseX, WEBGL) appeared pink. This styling was missing in the CM6 branch.

Demo:

after fix :

befor fix :

Changes:

• Added p5Highlight.js — a CM6 ViewPlugin that walks the Lezer syntax tree over visible ranges, checks each VariableName and VariableDefinition node against the p5 keyword lists from p5-keywords.js, and applies cm-p5-function or cm-p5-variable decorations
• Updated _editor.scss — added styles for .cm-p5-function (bold blue) and .cm-p5-variable (pink) using existing theme variables so all three themes (light, dark, high-contrast) are supported
• Updated stateUtils.js — registered p5Highlight in the extensions array

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• has no typecheck errors (npm run typecheck)
• is from a uniquely-named feature branch and is up to date with the develop-codemirror-v6 branch.
• is descriptively named and links to an issue number, i.e. Fixes #3868
• meets the standards outlined in the accessibility guidelines