fix: add Adapter alias for runtime adapter discovery

`molecule_runtime.adapters.get_adapter()` reads
`getattr(mod, "Adapter")` after importing ADAPTER_MODULE.
Without the alias the workspace startup fails preflight with
"no \`Adapter\` class is exported".

Same fix already shipped in claude-code, hermes, gemini-cli,
langgraph, deepagents today. Surfaced by today's wire-real E2E
sweep against fresh template images. The new bare-imports lint
in molecule-ci PR #8 catches related issues automatically.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

adapter.py

@@ -142,3 +142,6 @@ class CrewAIA2AExecutor(AgentExecutor):
 
     async def cancel(self, context, event_queue):  # pragma: no cover
         pass
+
+
+Adapter = CrewAIAdapter