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/graph-validation.md

@@ -0,0 +1,39 @@
+---
+id: graph/validation
+name: Implement graph validation functions (validateSchema, validateGraph, validate)
+status: pending
+depends_on:
+  - graph/flowgraph-class
+  - error/hierarchy
+scope: narrow
+risk: low
+impact: component
+level: implementation
+---
+
+## Description
+
+Implement the validation functions that check graph integrity. These never throw — they collect issues and return structured error arrays. This follows the returning (not throwing) contract per error-handling.md.
+
+## Acceptance Criteria
+
+- [ ] `validateSchema<NodeAttrs>(graph, NodeAttrsSchema): ValidationError[]` — checks each node's attributes against the TypeBox schema using `Value.Errors()`, returns `ValidationError[]`
+- [ ] `validateGraph(graph): GraphValidationError[]` — checks for cycles, dangling references, orphan nodes, status inconsistencies; returns `GraphValidationError[]`
+- [ ] `validate(graph): AnyValidationError[]` — runs both schema and graph validation, returns combined `AnyValidationError[]`
+- [ ] All validation functions use the "collect all errors" pattern — never throw, never short-circuit
+- [ ] `GraphValidationError` categories: `cycle` (with cycle paths), `dangling-reference` (with source/target), `orphan-node` (with node key), `status-inconsistency` (with node/parent status details)
+- [ ] Unit tests: valid graph returns empty array, each category of error detected, multiple errors collected
+
+## References
+
+- docs/architecture/error-handling.md — validation result types, collecting errors
+- docs/architecture/analysis.md — validateGraph, validate functions
+- docs/architecture/flowgraph-api.md — validate convenience method
+
+## Notes
+
+> To be filled by implementation agent
+
+## Summary
+
+> To be filled on completion