Style the engine's own logs, notice enrolment while serving, say more in status

Four things from a testing pass.

`fluksio serve` printed its own lines through the root logger, which has no
handler and falls back to `INFO:fluksio.cloud.connector:...` — beside uvicorn's
aligned output it reads like something went wrong. The engine's loggers and
alembic's now use uvicorn's own handler. Named rather than configuring the
root: httpx logs every portal call at INFO and none of that is printed today.

`fluksio enroll` writes its config from another process, so an engine already
serving never learned it had been paired. It now looks for one every few
seconds and dials when it appears. `load()` rather than `exists()`, or a file
that does not parse would be restarted forever.

`fluksio status` says where the installation stands with its portal — never
paired, linked, or paired and unreachable, which is the one worth acting on.

`--seed` and `--timeout` had no help text at all. Both say what they are for
now, and the docs say what a seed is actually for: recorded on the run, part of
its input digest, and passed to an input named `seed` when the flow declares
one, so the number a run is labelled with is the one the code drew from.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019V5bsYGNxcgPs4xXmTPx69

backend/fluksio/sdk/client.py

@@ -206,6 +206,11 @@ class Client:
         result: dict[str, Any] = self._call("GET", "/observability/summary")
         return result
 
+    def cloud_status(self) -> dict[str, Any]:
+        """Whether this installation is enrolled with a portal, and linked."""
+        result: dict[str, Any] = self._call("GET", "/cloud/status")
+        return result
+
     def events(self, kind: str = "failure", limit: int = 10) -> list[dict[str, Any]]:
         """What went wrong, or who changed what. Newest first."""
         result = self._call(