feat(data): add seed loader protocol with relationship resolution & dependency ordering

Add seed-loader.zod.ts with Zod schemas for:
- ReferenceResolutionSchema: field reference resolution via externalId
- ObjectDependencyNodeSchema/GraphSchema: topological sort for insert order
- ReferenceResolutionErrorSchema: actionable error reporting
- SeedLoaderConfigSchema: dry-run, multi-pass, batch, transaction config
- DatasetLoadResultSchema: per-object load statistics
- SeedLoaderResultSchema: complete load result with summary
- SeedLoaderRequestSchema: request combining datasets + config

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

packages/spec/src/data/index.ts

@@ -14,6 +14,9 @@ export * from './driver-nosql.zod';
 
 export * from './dataset.zod';
 
+// Seed Loader Protocol (Relationship Resolution & Dependency Ordering)
+export * from './seed-loader.zod';
+
 // Document Management Protocol
 export * from './document.zod';