Update npm dependencies and fix breaking API changes

[AnHeuermann]

Summary

• Bump all npm packages to latest versions: TypeScript 5→6, ESLint 8→10, mocha 10→11, web-tree-sitter 0.20→0.26, vscode-languageclient 8→9, esbuild 0.20→0.28, @types/node 20→25, and others
• Update CI to Node.js 24 LTS

Breaking changes fixed

web-tree-sitter v0.26 API changes:

• Rename SyntaxNode→Node, add named imports for Tree, Language, Edit, Point throughout the codebase
• Use new Edit class constructor for tree.edit() calls
• Replace callback-based incremental parse with byte-index approach to correctly handle newlines
• Update tree-sitter-modelica.wasm to v0.2.2 (dylink.0 format required by v0.26 runtime)

esbuild bundling fix:

• Alias web-tree-sitter to its CJS build in esbuild.config.js; the ESM build uses import.meta.url which esbuild shims as undefined in CJS output, causing createRequire(undefined) to throw at startup

ESLint 9+ flat config migration:

• Replace .eslintrc.js + .eslintignore with eslint.config.js using the new flat config format
• Install @eslint/js and globals packages

Mocha v11 + Node.js 24 test runner fix:

• Node.js 24 has native TypeScript strip support (process.features.typescript === 'strip'), which causes mocha to bypass ts-node/register for .ts files
• Switch from ts-node/register to tsx/cjs as the mocha require hook

TypeScript 6 fixes:

• Add ignoreDeprecations: "6.0" for moduleResolution: node deprecation
• Add skipLibCheck: true and update lib/target to es2022
• Fix lint issues surfaced by stricter rules (no-redeclare, unused expressions, comma-expressions)

Other fixes:

• Remove unused native tree-sitter addon (only web-tree-sitter is used at runtime)
• Replace @nodelib/fs.walk with fs.readdir({ recursive: true, withFileTypes: true })

Test plan

• npm run lint — clean
• npm run esbuild — builds successfully, no import_meta references in bundle
• npm run test:server — 20/20 unit tests pass
• npm run test:e2e — 3/3 integration tests pass (requires display / WSLg)
• CI passes on ubuntu-latest with Xvfb