feat(#238): scaffold rings/ for trios-kg — KG-00, KG-01, KG-02, BR-OUTPUT

[gHashTag]

Refs #238

Summary

Adds organizational ring scaffold for trios-kg (Tier 2 SILVER) per issue #238.

Rings

• KG-00 — graph (trios-kg-kg00)
• KG-01 — query (trios-kg-kg01)
• KG-02 — index (trios-kg-kg02)
• BR-OUTPUT — assembly (trios-kg-broutput)

Ring diagram

BR-OUTPUT (assembly)
    ↓
  KG-00   KG-01   KG-02 

Method (additive scaffold only)

• src/ is untouched — existing logic stays where it lives.
• rings/ directory added in parallel; each ring is its own workspace package with stub types + ≥1 passing unit test.
• Top-level RING.md and AGENTS.md document the future logic-migration plan.
• Each ring's TASK.md is marked scaffolded — logic migration: TODO.
• Workspace members updated in root Cargo.toml.

Verification

cargo check status: fail

BLOCKED: cargo check reported issues — see commit log / CI.

Anchor

phi^2 + phi^-2 = 3 · TRINITY · NEVER STOP

Compliance

• R1: Rust only ✅
• R9: ring isolation (no cross-imports except via Cargo.toml) ✅
• L7: experience line will be posted via gh issue comment 238

🤖 Generated with Claude Code

[gHashTag]

Note: cargo check -p trios-kg reports "package ID did not match any packages" — trios-kg is not registered as a workspace member of the root Cargo.toml (pre-existing). All 4 ring packages (KG-00, KG-01, KG-02, BR-OUTPUT) themselves cargo check clean. Scaffold itself is green.