fix: preserve query string on automatic redirects

[WilliamK112]

Summary

• preserve the original query string for serve-handler's automatic redirects
• limit the behavior change to cleanUrls and trailingSlash redirects
• add integration coverage for both redirect paths

Problem

Requests such as /directory/clean-file.html?foo=bar currently redirect to /directory/clean-file, dropping the original query string. The same thing happens for automatic trailing slash redirects.

Scope

This patch keeps the change narrow on purpose: it preserves the query string only for redirects generated internally by cleanUrls and trailingSlash. It does not change the behavior of user-configured redirects.

Testing

• corepack yarn build-views
• corepack yarn jest test/integration.test.js --runInBand --forceExit

Fixes #178