feat(napi): expose findTsconfig methods in Node API

[sapphi-red]

Exposed find_tsconfig from the napi apis.

I'm planning to use this at https://github.com/rolldown/rolldown/blob/25e16ff133930d7d75453b036a63ecf84f19f184/packages/rolldown/src/utils/resolve-tsconfig.ts#L29 and re-export it from Vite for vitejs/vite#22336

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.78%. Comparing base (bf29bf0) to head (a3043ca).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1403   +/-   ##
=======================================
  Coverage   94.78%   94.78%           
=======================================
  Files          26       26           
  Lines        4828     4828           
=======================================
  Hits         4576     4576           
  Misses        252      252           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[codspeed]

Merging this PR will improve performance by 4.46%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 2 improved benchmarks
✅ 19 untouched benchmarks
⏩ 5 skipped benchmarks¹

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	resolver_real[multi-thread]	541.7 µs	514.7 µs	+5.25%
⚡	pm/pnpm-isolated	2.1 ms	2 ms	+3.68%

Tip

Curious why performance improved? Comment @codspeedbot explain why performance improved on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing feat/find-tsconfig (a3043ca) with main (bf29bf0)}

Footnotes

1. 5 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩