Fix repeated SearchProvider index rebuilds

[avinxshKD]

Fixes #1249

Summary

• fetch and build the Fuse index only when the locale changes
• reuse the index for subsequent submitted searches
• clear stale results while a new locale index loads
• abort stale index requests during cleanup
• describe searchable aliases in the index type

Testing

• npx vitest run test/components/SearchProvider.test.tsx --project DOM --reporter=verbose
• npx eslint src/components/SearchProvider/index.tsx test/components/SearchProvider.test.tsx
• npm run check

[avinxshKD]

@ksen0 @doradocodes pls take a look, kept focused fixes as discussed (search fetch/index flow + postMessage origin hardening)

[doradocodes]

@avinxshKD From my understanding, this PR includes 2 different fixes:

1. Fixes the issue with SearchProvider that rebuilds even when locale hasn't changed
2. The use of * in postMessage() for iframes

If that is the case, it's important that we have 2 different issues created and 2 separate PRs to fix them. This helps keep things organized for the repo. Please update the original issue #1249 to have an accurate title+description, and create a new issue if relevant. Then have 2 PRs for the each of those issues. Thanks!

[doradocodes]

Hi @avinxshKD, following up on this. Are you still working on it?

[Nwakaego-Ego]

Hi @avinxshKD, this is the third follow-up on this PR. Are you still available to work on this? If you are facing any issues or are no longer able to continue, please let us know. Thank you for your work on this so far

[avinxshKD]

Hi @avinxshKD, this is the third follow-up on this PR. Are you still available to work on this? If you are facing any issues or are no longer able to continue, please let us know. Thank you for your work on this so far

Im so sorry, was really busy with work and studies. Can i pick this up on this weekend?
Thankyou so much @Nwakaego-Ego

[avinxshKD]

@doradocodes @Nwakaego-Ego sorry this took so long. I've split the work as requested:

#1249 and this PR now cover only the SearchProvider fetch/index flow
#1605 tracks the iframe postMessage origin issue
#1606 contains the separate postMessage fix
The title and description of #1249 and this PR have also been updated to match their scope.

PTAL when get chance :p.

[Nwakaego-Ego]

Thank you, @avinxshKD, for your work on this PR. I tested the issue again on the live websites before reviewing the fix. Typing a search term character by character did not make repeated requests. However, submitting circle and then color produced two separate requests for the same en.json file. This confirms that the problem happens when different search terms are submitted, not on every keystroke.

I also tested this PR locally:

• submitting circle and color produced only one en.json request;
• after switching to Spanish, submitting el color and crear produced only one es.json request;
• both SearchProvider tests passed;

The fix works as expected in my local testing.

cc @doradocodes