fix: isolate tuple searchParams in init hooks

[atharvasingh7007]

Summary

• isolate searchParams tuple arrays before init hooks mutate them
• prevent tuple edits from leaking into later requests on the same instance
• add a regression test covering the supported [[key, value]] search params form

Root cause

cloneInitHookOptions() is supposed to give init hooks a request-local mutable copy of the options, but searchParams in tuple-array form only got a shallow outer array copy. Mutating an existing tuple like options.searchParams[0][1] = ... changed the shared default tuple, so the next request inherited the previous hook mutation.

Fix

• add a cloneSearchParametersForInitHook() helper that deep-copies tuple arrays while preserving the other supported searchParams input forms
• keep the existing cloning behavior for strings, objects, and URLSearchParams
• add an end-to-end init-hook regression that proves tuple-array defaults no longer leak between requests

Testing

• npm run build
• npx ava test/hooks.ts --match "init hook*do not leak across requests"
• npx ava test/hooks.ts --match "init hook tuple searchParams mutations do not leak across requests"

Notes

npm test in this Windows checkout still hits upstream xo project-service parsing errors for the repo's test files before it reaches AVA. The targeted hook tests and build above passed locally.