Convert source from JavaScript to TypeScript

[Copilot]

Migrates all 46 src/ files from .js to .ts and wires up the TypeScript toolchain. Uses lenient compiler settings (strict: false, noImplicitAny: false) so existing code compiles unchanged — this establishes the infrastructure for incremental type annotation.

Toolchain

• tsconfig.json — moduleResolution: bundler, noEmit: true, ignoreDeprecations: "6.0", baseUrl: ./src
• webpack.config.js — entry → blockpy.ts; ts-loader (transpileOnly) + babel-loader pipeline; .ts added to resolve.extensions; removed deprecated eslint-loader (replaced by standalone npm run lint)
• .eslintrc.json — parser swapped to @typescript-eslint/parser; original rules unchanged
• package.json — adds "lint": "eslint src/" script; new devDeps: typescript@6, ts-loader@8, eslint@8, @typescript-eslint/{parser,eslint-plugin}, @types/{jquery,knockout}

Source

• All 46 src/**/*.js → .ts
• 17 imports with explicit .js extensions stripped
• src/globals.d.ts — declares script-tag globals (Sk, Blockly, FilePond) as any