refactor(mcp): migrate mcp_service/index.js to TypeScript

[devin-ai-integration]

SUMMARY

Migrates the Node.js entry point superset/mcp_service/index.js to TypeScript, per the ongoing "NO JavaScript files" frontend modernization.

• Replaces index.js with index.ts: the SupersetMCPServer class is now fully typed. Constructor options are captured in a SupersetMCPServer.Options interface (with a Transport = 'http' | 'stdio' union), and the internal subprocess handle is typed as ChildProcess | null (via child_process). Unused requires (spawn, path) from the original file were dropped.
• Preserves the existing CommonJS consumption contract. The module is authored with export = SupersetMCPServer, so tsc emits module.exports = SupersetMCPServer — require('@superset/mcp-server') still returns the class directly, unchanged from before.
• Adds a scoped tsconfig.json (strict, CommonJS target, declaration: true, outDir: dist) that compiles only index.ts.
• Updates package.json:
  • main → dist/index.js, adds types → dist/index.d.ts
  • adds build (tsc -p tsconfig.json) and prepublishOnly scripts
  • adds files: [dist, bin]
  • adds typescript and @types/node devDependencies (+ package-lock.json)

dist/ is already covered by the repo root .gitignore, so build artifacts are produced on npm run build / publish rather than committed. The bin/superset-mcp.js runner is unchanged (out of scope).

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

N/A

TESTING INSTRUCTIONS

cd superset/mcp_service
npm install
npm run build            # tsc compiles index.ts -> dist/index.{js,d.ts}
node -e "const S=require('./dist/index.js'); const s=new S({port:6000}); console.log(typeof S, typeof s.start, typeof s.stop)"
# -> function function function

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

Link to Devin session: https://app.devin.ai/sessions/e148ac05a34d410aa25f94e955c07f48
Requested by: @shayanshafii

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