Introduce shared/state.ts as a service-locator so popup components
(item-detail, item-form, trash, devices, settings, etc.) work in both
the popup and vault tab bundles. Both entry points register themselves
as the host; components import from shared/state instead of popup.ts.
Vault.ts now delegates to the real popup components, removing ~300 lines
of placeholder renderers.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Shows current + historical values for tracked fields (password/concealed).
Click to reveal, copy button per entry (plaintext stored in a module-level
Map, never embedded in the DOM). Grouped by field name if multiple tracked
fields exist. Adds historyItemId to PopupState and 'field-history' to View.
Co-Authored-By: Claude <noreply@anthropic.com>
