feat(marketplace): add domain metadata to all plugins [BREAKING]

- domain field required in plugin.json and marketplace.json (core/data/ops)
- validate-marketplace.sh enforces domain presence and allowed values
- claude-launch.sh new profiles: saas, ops, debug; infra deprecated
- CANONICAL-PATHS.md and CLAUDE.md updated with domain conventions

BREAKING CHANGE: validate-marketplace.sh rejects plugins without domain field

Version: 8.0.0

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/project-hygiene/.claude-plugin/plugin.json

@@ -28,5 +28,6 @@
         ]
       }
     ]
-  }
+  },
+  "domain": "core"
 }