Merge main into fix/db-off-data-plane-469

Brings in main's 8 commits — #470 (backend-agnostic CI guards: BackendStatus
enum, quiet status(), is_backend_available/is_backend_ready, tests/_backend.py
skip_unless_backend) plus firecracker status() readiness checks (kvm/kernel/
dropbear/mke2fs).

Reconciled #470's additions into the reorg'd backend structure:
  * BackendStatus enum + the status(*, quiet=) ABC signature -> backend/base.py
  * is_backend_available / is_backend_ready -> backend/selection.py
  * exposed all three through the lazy backend facade (__init__).
Integration-test conflicts were our control_plane->orchestrator renames vs
main's skip_unless_docker -> skip_unless_backend swap: kept our refactored
import paths + main's guard. Repointed main's new is_backend_* tests to patch
selection._backends (our moved home) instead of the facade.

pyright: 0 errors. Full unit suite green (2272).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

bot_bottle/backend/docker/backend.py

@@ -20,7 +20,8 @@ infrastructure: CA install and git copy-in.
 from __future__ import annotations
 
 import shutil
-from contextlib import contextmanager
+import io
+from contextlib import contextmanager, redirect_stderr
 from pathlib import Path
 from typing import Generator, Sequence
 
@@ -60,8 +61,11 @@ class DockerBottleBackend(BottleBackend["DockerBottlePlan", "DockerBottleCleanup
         return _setup.setup()
 
     @classmethod
-    def status(cls) -> int:
+    def status(cls, *, quiet: bool = False) -> int:
         from . import setup as _setup
+        if quiet:
+            with redirect_stderr(io.StringIO()):
+                return _setup.status()
         return _setup.status()
 
     @classmethod