docs: README v6.0 + ADR-001 Message Protocol Foundation

README updates:
- Full repository tree structure (was outdated skeleton)
- Added Message Protocol namespace summary (NATS)
- New ADR section with link to ADR-001
- Added nyx-substrate to related projects
- New philosophy: "Infrastructure is geology, models are weather"
- Version bump 5.0 → 6.0

ADR-001 captures Silvester interview decisions:
- Single NATS bus with dev/staging namespaces
- Staged schema versioning with topic separation
- Echo agent first (YAGNI principle)
- MCP Server with heartbeat-based subscription delivery

🎆 Silvester 2025 edition

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

architecture/adr/README.md

@@ -0,0 +1,96 @@
+# Architecture Decision Records
+
+This directory contains Architecture Decision Records (ADRs) for the Nimmerverse Sensory Network.
+
+---
+
+## What is an ADR?
+
+An ADR captures an important architectural decision made along with its context and consequences. They serve as:
+
+- **Documentation** of why decisions were made
+- **Onboarding** for future contributors (including future Nyx instances)
+- **Historical record** for understanding evolution
+
+---
+
+## ADR Index
+
+| ADR | Title | Status | Date |
+|-----|-------|--------|------|
+| [001](ADR-001-message-protocol-foundation.md) | Message Protocol Foundation | Accepted | 2025-12-31 |
+
+---
+
+## ADR Lifecycle
+
+```
+PROPOSED → ACCEPTED → DEPRECATED → SUPERSEDED
+              │                        │
+              └───────────────────────▶│
+                   (can be superseded)
+```
+
+**Statuses:**
+- **Proposed** - Under discussion, not yet decided
+- **Accepted** - Decision made, being implemented
+- **Deprecated** - No longer recommended, but still valid for existing code
+- **Superseded** - Replaced by newer ADR (link to replacement)
+
+---
+
+## Template
+
+```markdown
+# ADR-XXX: Title
+
+**Status:** Proposed | Accepted | Deprecated | Superseded by ADR-YYY
+**Date:** YYYY-MM-DD
+**Decision Makers:** who was involved
+**Context:** brief session/discussion context
+
+---
+
+## Context
+
+Why is this decision needed? What problem are we solving?
+
+---
+
+## Decision
+
+What did we decide? Be specific.
+
+---
+
+## Consequences
+
+### Enables
+What does this decision make possible?
+
+### Constrains
+What does this decision limit?
+
+### Deferred
+What are we explicitly not deciding now?
+
+---
+
+## References
+
+Links to related documents, discussions, code.
+```
+
+---
+
+## Philosophy
+
+> "The best time to document a decision is when you make it.
+> The second best time is now."
+
+ADRs are written in partnership. They capture dialogue, not just conclusions.
+
+---
+
+**Created:** 2025-12-31
+**Maintainers:** dafit, Nyx