Generic repeatable-entry CRUD pattern

Description

The add / view / edit / delete component that every Phase 1 list screen is built
on. Nine of the seventeen Phase 1 feature tickets are variants of it, so this is
the highest-leverage ticket in the phase and everything else waits on it.

This ticket and #35 are the same piece of work and are tracked together as
#118, which has the fuller specification. Work #118.

The storage half already exists: createRepository({ table, fields }) in
mobile/src/lib/db/repository.ts gives list / find / create / update / remove
against the encrypted database, with getDatabase injectable so the component
can be tested without a device. What is missing is the UI half.

Acceptance Criteria

• A reusable component, not a screen with the field list hardcoded
• Driven by a declared field list, matching how createRepository is configured
• Add, edit and delete all work end to end against the encrypted local database
• Delete asks for confirmation — the data is local-only and there is no undo (0001)
• Empty state, loading state and error state all handled
• WCAG-aligned: screen reader support, no reliance on colour alone, adequate touch targets
• One task per screen; the next step is obvious
• Covered by unit tests, driven through an injected repository rather than a real database

Additional Info and Resources

• Duplicate of / superseded by #118
• Later screens copy this directly, so the seams matter more than the polish. A field list, labels, and validation hooks are the extension points the next nine tickets need
• Tests need no native build, so this component can be developed and tested without Xcode or Android Studio

QA

• See #118.

Do not start this ticket independently: it is superseded by #118, which contains the fuller specification. Read mobile/src/lib/db/repository.ts and the local-only architecture decision in docs/decisions/0001-local-only-architecture.md, then use #118's requirements to define the reusable component, injected-repository tests, and end-to-end CRUD behavior.