Fix iOS 18 cookie loading issue

[google-labs-jules]

This change updates GenericCookieHandler.getAllCookies to handle a regression in iOS 18 (Safari) where cookies.getAll returns an empty array if storeId is not explicitly handled or if the default store lookup fails.

The fix involves:

1. Detecting if the browser is Safari.
2. Fetching all available cookie stores using browser.cookies.getAllCookieStores().
3. Iterating through each store and fetching cookies for the current tab's URL with the specific storeId.
4. Aggregating the results and returning the flattened list of cookies.

This ensures cookies are correctly retrieved on iOS 18 while preserving existing behavior for other browsers.

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PR created automatically by Jules for task 14413639943233490940 started by @Moustachauve

[google-labs-jules]

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