feat(FN-1188): add Agent Companies parser and core exports

- Add Agent Companies manifest types for company, team, agent, project, task, and skill files
- Implement YAML frontmatter parsing, directory/tar.gz package parsing, and contextual parse errors
- Convert agent manifests to AgentCreateInput with role inference and skip-existing import support
- Export Agent Companies parser/type APIs from @fusion/core and add the yaml dependency
- Add comprehensive parser and type tests covering happy paths, archive handling, and validation failures

packages/core/package.json

@@ -35,6 +35,7 @@
   },
   "private": true,
   "dependencies": {
-    "cron-parser": "^5.5.0"
+    "cron-parser": "^5.5.0",
+    "yaml": "^2.8.3"
   }
 }