Make item detail pages match the new editor design

The new editor (VAULT-9, #606) looks good, but next to it the read-only item pages now look old and out of step. Viewing and editing an item should look like the same page, so switching between them with Edit and Done feels like one page changing mode rather than a different screen.

The editor now has:

• the item's badge, name and subtitle at the top (DetailEditorItemBadge with DetailEditorItemIdentity)
• cards with colored icon tiles, on DetailEditorRowBackground
• step headers
• a prominent Delete button

The read-only pages still use the old form. OTPCodeDetailView, SecureNoteDetailView and RecoveryPhraseDetailView all go through VaultItemDetailView, and they show:

• the item's preview card in a section header
• a plain Description section
• a collapsed "Metadata" disclosure row (MetadataDisclosureSection)
• tags floating in its footer

What to change:

• Use the editor's header, card style, icon tiles and typography on the read-only pages too.
• Keep what each page is for:
  • the live code you can tap to copy
  • the note's text
  • the phrase's words, with masking, hide-while-captured and locking all behaving as now
  • the description, tags and metadata
• Cover the locked states and encrypted items (EncryptedItemDetailView) as well.
• Don't show whether a killphrase is set, just as the editor overview doesn't (MANIFESTO.md C5).

Tests:

• Re-record the detail view snapshot tests for all three item types.
• Several of them record "dark" images that are actually light (VAULT-14). Fix that while re-recording, using .environment(\.colorScheme, …).
• Take before and after screenshots of each type in the simulator, in view and edit mode.