docs: restructure architecture docs to flowgraph pattern

- Create decisions/ directory with 32 numbered ADRs (ADR-001 through ADR-032)
  extracted from inline DD/SD/ED/SE decision sections
- Create open-questions.md with 16 OQs organized by theme, cross-referenced
  to ADRs, with status tracking (resolved/open)
- Create README.md as architecture index with doc table, ADR table, and
  lifecycle status definitions (draft/reviewed/stable/deprecated)
- Replace inline decision sections in all spec docs with ADR reference tables
- Replace inline open questions with OQ references to centralized tracker
- Update frontmatter: metagraph-module.md, overview.md, sqlite-host.md → reviewed;
  schema-evolution.md and encrypted-data.md remain draft
- DD1-DD10 → ADR-009 through ADR-018
- D1-D8 → ADR-001 through ADR-008
- SD1-SD5 → ADR-019 through ADR-023 (SD5 folded into ADR-006/008)
- ED1-ED5 → ADR-023 through ADR-027
- SE1-SE5 → ADR-028 through ADR-032

docs/architecture/decisions/016-naming-convention-for-module-entries.md

@@ -0,0 +1,25 @@
+# ADR-016: Naming convention for Module entries
+
+## Status
+
+Accepted
+
+## Context
+
+Module entries need a way to distinguish their role (config, node type, edge type, constraint) so that `moduleToDbSchema()` can map them to the correct DB tables. Two approaches: explicit metadata/decorators on entries, or naming convention with role-distinguishing suffixes.
+
+## Decision
+
+Module entries use role-distinguishing suffixes: `*Node` for node types, `*Edge` for edge types, `Config` for graph configuration, `*EdgeConstraints` for edge endpoint constraints, and bare names or `*Enum` for shared types. `moduleToDbSchema()` uses this convention to map entries to DB tables.
+
+Explicit metadata/decorators (e.g., `{ kind: "nodeType", name: "call", schema: ... }`) were considered but rejected — they add boilerplate without adding information. The suffix convention is simpler and sufficient for the expected Module size (5–20 entries).
+
+## Consequences
+
+- `moduleToDbSchema()` throws on entries that don't match any recognized suffix
+- Bare names without a suffix are treated as shared types (embedded in other entries' schemas), not as independent DB rows
+- `*EdgeConstraints` entries must have an `edgeType` field matching an `*Edge` entry name
+
+## References
+
+- [metagraph-module.md](../metagraph-module.md)