Add upstream state and convergence specification

[mdheller]

Summary

Adds docs/specs/08_UPSTREAM_STATE_AND_CONVERGENCE_SPEC.md as the controlling spec for moving HellGraph forward from the actual current upstream state.

This corrects the stale Rust-only framing and documents the current polyglot architecture:

• TypeScript OpenCog-compatible AtomSpace/metagraph engine
• PLN, ECAN, pattern matcher, SPARQL, Gremlin, SHACL, Turtle, Atomese
• ingestion, semantic/vector pipeline, brain import/export, sidecar, StorageNode, RocksDB backend
• Rust kernel/runtime crates plus hg_analytics
• deterministic Rust analytics: PageRank, warm-start PageRank, Brandes betweenness, Louvain

Main corrections

• Root README underclaims implemented TS surfaces.
• package.json says UNLICENSED while root repo has MIT license.
• SPARQL/Gremlin/semantic vectors are not merely future work; they exist in the TS engine.
• Rust is the deterministic kernel/convergence plane, not the only current implementation.
• Parity must be split across Blazegraph RDF/SPARQL, Neptune Database, Neptune Analytics, OpenCog/AtomSpace, and GraphRAG/ML surfaces.

Follow-up PRs proposed by the spec

1. Correct README and license/package metadata.
2. Add TypeScript CI gates alongside Rust CI.
3. Add conformance fixtures for SPARQL, Gremlin, semantic search, brain import/export, and Rust analytics.
4. Add a Neptune parity matrix as a separate spec.

Validation

Documentation-only PR. No runtime code changed.