Fix: Case-insensitive Cyrillic search & nickname lookup logic (#140)

[LordMikkel]

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Describe briefly what your pull request changes. Focus on the value provided to users.

Fixes #140 issue

Previously, the search relied on SQL LIKE queries, which are often case-sensitive for non-ASCII characters (e.g., Russian). Searching for "борис" would not find "БОРИС".
Fix: Switched contact filtering to in-memory JavaScript using .toLocaleLowerCase(), which handles Unicode case-folding correctly.

Test approach:

• Manual Testing:
  • Verified that searching for a contact with a Cyrillic name (e.g., "БОРИС") works correctly when typing in lowercase ("борис").
  • Verified that searching for a contact's real Profile Name (e.g., "Mikel") works successfully even when the contact has a Nickname set (e.g., "БОРИС").
• OS: Linux / GNOME

[Bilb]

This is going to be way too slow and expensive for a large database.
This has to happen on the database itself, through searchConversations.

Can you make it work that way

[LordMikkel]

@Bilb Thanks for the feedback regarding performance! You were absolutely right.

I've discarded the in-memory filtering logic.
I refactored the solution to keep the logic strictly within the database.

Ready for re-review!

[Bilb]

I see the issue now. I thought sqlite3 could handle those, but it seems we don't have the plugin for it (ICU).

In this case, I think your memory approach was actually better but with a few tweaks.

Don't do a Data.getAllConversations in a36100a#diff-955956e9166338a3c122082f7848584c67e47ed13be9a8faec27f08c4d9684c3L84-L105 as this is quite slow on a large db.
Those conversations are already cached. You should be able to do your search on them directly with something like

function convoMatchesSearch(convo, searchTerm) {
    const searchTermLower = searchTerm.toLowerCase();
  return (
    convo.id.toLowerCase().includes(searchTermLower) ||
    convo.nickname?.toLowerCase().includes(searchTermLower) ||
    convo.displayNameInProfile?.toLowerCase().includes(searchTermLower)
  );
}

That you can use with

for (const id in window.inboxStore.getState().conversations.conversationLookup) {
  const convo = window.inboxStore.getState().conversations.conversationLookup[id];
  if (convoMatchesSearch(convo, searchTerm)) {
    results.push(convo);
  }
}

This should be enough.
Once you've updated your PR, I'll give it a go on large DB to make sure the performance are fine