fix: revert broken merge and restore refactored SDK architecture

[EricSanchezok]

Summary

• Revert broken merge (d731105) that incorrectly mixed old chunked transport code (from cyl_dev branch) into the refactored SDK, causing 120+ TypeScript build errors
• Restore core/sdk/transport-archive sources to their correct post-refactoring state (7b3198b)
• Remove chunked transport files and docs (not adapting for now — old code is incompatible with the new architecture)
• Untrack gitignored directories (experiments/, examples/) that were re-added to the index during file restoration
• Unignore docs/paper/figs/ so README-referenced images (architecture diagram, demo screenshots) are properly tracked
• Rewrite README for SII-Holos org with updated repo URLs, architecture diagrams, and demo content

What was wrong

Merge d731105 resolved conflicts incorrectly between the cyl_dev chunked transport branch and the refactored SDK. This reintroduced old type names (workDir, ArchiveTransport, PendingInvitation, etc.) into the new manager-based architecture, breaking the build.

Verification

• CI pipeline: build ✅ typecheck ✅ 156 tests pass ✅
• All 8 experiment scenarios run successfully (01-local-basic through 08-git-transport)