feat: allow adding websites while blocked - #111

Change

While anything is blocked, the Custom Domains editor in App Select now allows adding websites. Removing them stays locked: there are no delete buttons and no swipe to delete.

• Adding only saves the website to the list. Nothing is blocked automatically; to block it, tap Block All, which Home shows while the selection is partly blocked.
• The blocked footer now reads "Unblock all apps to remove custom domains." The string catalog entry is renamed to match.
• The Custom Domains row is no longer dimmed while blocked.

If a website is added during a timed unblock of all apps, App Select's existing save (updateMainSelection) adds it to that unblock, so it is blocked when the unblock ends. This applies to any edit during a timed unblock and isn't new.

Tests

testCustomDomainsEditorIsReadOnlyWhileBlocked is now testCustomDomainsEditorAddsButDoesNotRemoveWhileBlocked. It starts with only example.com blocked and checks that:

• example.com can't be removed;
• reddit.com can be added and can't be removed;
• Home then shows Block All, because the new website isn't blocked yet.

Results:

• NormalUITests class on iPhone 17, iOS 27: 11/11.
• Full unit suite: 879/879.
• With removal allowed (canRemove: true), the new test fails: "Websites can't be removed while blocked".