docs: sync wave-3 tracker and GitHub Pages (May 2026)

[PurHur]

Summary

• Updates docs/roadmap-wave3.md with language 9/13 merged on master and PR links (feat: enum declarations (basic VM) (#1356) #1463–feat(lang): __serialize / __unserialize magic methods (#1365) #1477, JIT: Complete first-class callable lowering (#1363) #1472, JIT: variable variables with compile-time names (#1226) #1381).
• Refreshes GitHub Pages sources: docs/pages/index.html, docs/pages/development-status.md (M2 301/532, wave-3 language progress, overall ~50%).
• README M2 spine count and wave-3 summary line.

Open follow-ups (not in this PR)

• Merge/rebase: #1473 readonly, #1478 weak refs, #1404 debug_backtrace
• New work: #1354 attributes

Test plan

• Review rendered Pages after merge (index + development-status)
• Cross-check docs/roadmap-wave3.md against closed issues on GitHub

Made with Cursor

[PurHur]

Umbrella #1380 updated with May 2026 master snapshot.