feat(mcp): enhance multi-platform notification resilience and reactive wakeups

- AgentApiNotifier: Sort candidate process sessions by creation time descending to prioritize the latest active IDE session over stale PIDs. Implement automatic retry across candidate address/token pairs and persist working credentials to shared environment files (~/.gemini/jetski/.jetski_env and ~/.artemis/.artemis_env).
- DesktopNotifier: Enable native OS desktop toast notifications by default on macOS, Linux, and Windows unless explicitly disabled or running in CI. Ensure MCP installer sets ARTEMIS_DESKTOP_NOTIFY=true in generated IDE configurations.
- ScriptNotifier: Add universal command hook adapter (ARTEMIS_NOTIFY_CMD / MCP_NOTIFY_COMMAND) for custom IDE and CLI integration.
- Fault Isolation: Wrap CompositeNotifier and global notify entrypoint in strict try-except blocks to guarantee zero-crash execution even if any individual notifier fails.
- Tests & Docs: Add unit tests for session recovery, fault tolerance, script hook execution, and document multi-platform notification architecture in README.

artemis/interfaces/cli/commands/mcp.py

@@ -66,6 +66,7 @@ def _get_config_snippet(client: str, python_exe: str, project_root: str) -> dict
         "env": {
             "PYTHONUNBUFFERED": "1",
             "PYTHONPATH": project_root,
+            "ARTEMIS_DESKTOP_NOTIFY": "true",
         },
     }
     config_with_cwd = {**config_body, "cwd": project_root}