fix(unified-search): Send ISO date strings

[nfebe]

Send expected ISO date string values for since and until.

See :

server/lib/private/Search/Filter/DateTimeFilter.php

Line 23 in 3d6699d

$this->value = new DateTimeImmutable($value);

[provokateurin]

What is sent right now?

[joshtrichards]

Seems fine. From what I can tell, the pre-PR behavior already serializes Date params to ISO strings, but only implicitly. It might be worth adjusting the search() contract docs as well, or even instead:

server/core/src/services/UnifiedSearchService.js

Lines 48 to 49 in 13adaf9

	* @param {string} options.since the search
	* @param {string} options.until the search

e.g.

 * @param {string|undefined} options.since ISO datetime string
 * @param {string|undefined} options.until ISO datetime string

I was initially confused because the current JSDoc already says only strings are accepted, not Date objects. In practice, though, that seems misleading because the existing behavior relies on implicit serialization. This PR makes that behavior more explicit, which is good, but I’d still suggest the doc update for clarity.

[joshtrichards]

/compile

[joshtrichards]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Done — I resolved the merge conflicts and pushed the updates in commit 8f614d6 (including the prior conflict-resolution merge 8800ac3).