refactor: extract @uncaged/workflow-util-role from role-llm (#15)

Move pure role utilities (decorateRole, withDryRun, onFail, schemaDefaults)
into @uncaged/workflow-util-role. extractMetaOrThrow stays in role-llm
since it depends on LLM capabilities.

Dependency graph (no cycles):
  util-role → workflow
  role-llm → workflow, util-role
  committer → workflow, util-role, role-llm

Closes #15

tsconfig.json

@@ -17,6 +17,7 @@
   },
   "references": [
     { "path": "packages/workflow" },
+    { "path": "packages/workflow-util-role" },
     { "path": "packages/workflow-role-llm" },
     { "path": "packages/workflow-role-committer" },
     { "path": "packages/workflow-role-reviewer" },