Fix permanent entity lifespan display for v0.5.21 - #114

Entities with lifespans longer than 100 years now display Permanent in query results, entity details (including genesis entities and operation history), and transaction operations. Query results omit the expiry date and countdown for these entities, preventing the RangeError: Invalid Date caused by uint64-max expiry blocks.

The shared display rule uses the available block duration and a 365-day year, with a strict > 100 years threshold. Query results calculate the full lifetime from creation to expiry; the existing never-expiring sentinel is recognized even when block timing is unavailable. Exactly 100 years and shorter lifespans retain their existing display. This changes presentation only.

Validation:

• Reproduced the uint64-max rendering crash with a regression test before the fix.
• Frontend tests: 262 passed, 21 opt-in tests skipped; covers the threshold, varying block durations, creation-block offsets, missing metadata, and rendering permanent entities.
• bun run typecheck and bun run typecheck:frontend-tests passed.
• npm run build passed.

Release: bump the backend, frontend, and frontend lockfile to 0.5.21.