docs: restore Realm preview in README

[ael-dev3]

Summary

Restore the recent Genesis 001 Realm development preview in the current mainline README.

• Re-embed the screenshot removed during Alpha 0.3.11 release preparation.
• Restore its provenance record and exact PNG asset from commit f103514.
• Keep the current Alpha 0.3.11 README wording and live-status claims unchanged.

Validation

• git diff --check
• Verified the README image target exists.
• Verified PNG metadata (2198×1384 RGBA) and SHA-256 eb156adea5befbd786e13deb563fc118faecfafa52da86c9f49f0b5f1d39fb35.

Documentation-only change; no runtime, backend, deployment, or release state changes.

[ael-dev3]

Closing without integration. This restores the same 3.26 MB Alpha 0.3.8-era screenshot previously removed for submission readiness; it does not represent the current 0.3.12 coastline, rivers, or Stone Quarry presentation, includes visible public identities, and adds a separate provenance mini-page that works against the concise README direction. If a Realm preview returns later, it should be captured from the exact current release, privacy-scrubbed, optimized, and recorded in the existing asset inventory.

[ael-dev3]

Reopened on request. Rebased onto current main including Alpha 0.3.12 water projection repair (#75); the README structure and wording remain unchanged, with only the historical preview restoration carried forward.