fix(world-lab): archive large exports compactly

[christopherjnelson]

Summary

• replace multi-megabyte browser document uploads with compact export filters, original generation timestamp, and SHA-256 digest
• deterministically regenerate and verify the exact artifact in the Game API before SQLite persistence
• return a bounded artifact_changed response when experiment state changed and require regeneration
• abort stalled browser archive requests after ten seconds while preserving safe idempotent retry behavior
• retain legacy full-document archive request compatibility and update architecture, ADR, and testing documentation

Verification

• repository owner confirmed format, format check, lint, typecheck, tests, build, and Playwright E2E are green
• manually verified a real Full Safe 50-tick export in SQLite: 8 agents, 400 records, exactly 8 records across each of 50 ticks, no retention loss, no metric inconsistencies, no orphan rows, and SQLite integrity check ok

Verified experiment: 397c834e-9520-4bad-8cb0-8e6026b309d0