refactor(mcp_service): migrate index.js to TypeScript

[devin-ai-integration]

SUMMARY

Migrates superset/mcp_service/index.js to TypeScript (index.ts) per the repo's "NO JavaScript files" modernization guideline.

• Adds SupersetMCPServerOptions interface and Transport type; options is Required<SupersetMCPServerOptions> and process is typed as ChildProcess | null
• Converts CommonJS require/module.exports to ES import/export default
• Updates package.json main from index.js to index.ts

Verified with tsc --noEmit --strict (clean) and pre-commit hooks (passed).

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

N/A

TESTING INSTRUCTIONS

Type-check the file: superset-frontend/node_modules/.bin/tsc --noEmit --module commonjs --target es2020 --strict --esModuleInterop --typeRoots superset-frontend/node_modules/@types --types node superset/mcp_service/index.ts

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/93ef63ea0dda4d639ae1bbe93ec9a778
Requested by: @shayanshafii

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