refactor: replace Moderator function with ModeratorTable in WorkflowDefinition (#200)

- WorkflowDefinition.moderator → WorkflowDefinition.table (ModeratorTable)
- Moderator type + tableToModerator no longer exported from protocol/runtime
- tableToModerator internalized in workflow-execute engine layer
- WorkflowDescriptor gains graph: WorkflowGraph (auto-extracted from table)
- buildDescriptor extracts serializable graph edges from ModeratorTable
- validateWorkflowDescriptor validates graph structure
- All templates (develop, solve-issue) export table directly
- CLI init scaffold updated to use ModeratorTable
- 99 tests pass, 0 failures

packages/cli-workflow/__tests__/thread-cli.test.ts

@@ -36,6 +36,7 @@ const threadFixtureDescriptor = `export const descriptor = {
     only: { description: "only", schema: {} },
     noop: { description: "noop", schema: {} },
   },
+  graph: { edges: [] },
 };
 `;