decompose architecture into 38 atomic tasks across 12 parallel generations

Decompose the reviewed architecture specs into taskgraph-managed tasks:
- 2 setup tasks (project init, test infrastructure)
- 4 schema tasks (enums, node attrs, edge attrs, graph schemas)
- 1 error hierarchy task
- 6 graph tasks (FlowGraph class, 3 construction paths, queries, validation)
- 5 analysis tasks (type-compat, build-type-edges, ordering, template-validation, defaults)
- 5 component tasks (Operation, Sequential, Parallel, Conditional, Map)
- 2 host config tasks (GraphologyHostConfig, ReactiveHostConfig)
- 4 reactive tasks (WorkflowRoot, node-status, max-concurrency, retry-semantics)
- 3 review tasks (foundation, reactive-and-hosts, complete-library)
- 5 meta cluster tasks (schema, graph, component, reactive, analysis layers)
- 1 API exports task

Validated with taskgraph: zero cycles, 38 tasks, 12 parallel generations.
Critical path: 12 tasks through reactive execution layer.

tasks/meta-graph-layer.md

@@ -0,0 +1,39 @@
+---
+id: meta/graph-layer
+name: Complete graph layer — FlowGraph class, all construction paths, queries, validation
+status: pending
+depends_on:
+  - graph/flowgraph-class
+  - graph/construction-operation
+  - graph/construction-call
+  - graph/construction-json
+  - graph/queries
+  - graph/validation
+scope: system
+risk: medium
+impact: phase
+level: planning
+---
+
+## Description
+
+Meta task that clusters all graph module tasks. Once complete, the core FlowGraph class supports operation graph construction, call graph construction from events, JSON serialization, all query methods, and graph validation.
+
+## Acceptance Criteria
+
+- [ ] All graph tasks completed
+- [ ] FlowGraph class works for both `OperationGraph` and `CallGraph` type parameterizations
+- [ ] JSON round-trip is lossless
+- [ ] DAG invariants enforced at construction time
+
+## References
+
+- docs/architecture/flowgraph-api.md, docs/architecture/operation-graph.md, docs/architecture/call-graph.md
+
+## Notes
+
+> To be filled by implementation agent
+
+## Summary
+
+> To be filled on completion