Generated UI mock mode for no-chain frontend iteration

[snissn]

Background

Frontend iteration is blocked when no local chain/deploy is available.

Goal

Enable generated UI mock mode for rapid UI development without blockchain dependencies.

Scope

• Add mock data mode toggle in generated UI (env-based).
• Use schema-driven mock records for list/detail/new flows.
• Preserve route/field behavior parity with real mode where feasible.
• Clear UI badge indicating mock mode.

Implementation Notes

• Keep mock mode isolated from production behavior.
• Reuse schema metadata to generate realistic default values.

Acceptance Criteria

• Generated app can run and navigate fully in mock mode without RPC.
• Mock mode does not require deployment/manifest.
• Tests cover route rendering in mock mode.