refactor(restore)!: restore volume files via direct host rsync

Drop the alpine-rsync helper image: resolve the volume mountpoint with
docker volume inspect and rsync the backup straight into it. Removes the
--rsync-image flag and the E2E_RSYNC_IMAGE pre-pull; the e2e test
container now mounts /var/lib/docker rw so the direct restore can write.

BREAKING CHANGE: the restore 'files' subcommand no longer accepts
--rsync-image; rsync must be available on the host running baudolo.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/baudolo/restore/files.py

@@ -3,12 +3,10 @@ from __future__ import annotations
 import os
 import sys
 
-from .run import run, docker_volume_exists
+from .run import docker_volume_exists, run
 
 
-def restore_volume_files(
-    volume_name: str, backup_files_dir: str, *, rsync_image: str
-) -> int:
+def restore_volume_files(volume_name: str, backup_files_dir: str) -> int:
     if not os.path.isdir(backup_files_dir):
         print(f"ERROR: backup files dir not found: {backup_files_dir}", file=sys.stderr)
         return 2
@@ -19,21 +17,21 @@ def restore_volume_files(
     else:
         print(f"Volume {volume_name} already exists.")
 
-    # Keep behavior close to the old script: rsync -avv --delete
-    run(
-        [
-            "docker",
-            "run",
-            "--rm",
-            "-v",
-            f"{volume_name}:/recover/",
-            "-v",
-            f"{backup_files_dir}:/backup/",
-            rsync_image,
-            "sh",
-            "-lc",
-            "rsync -avv --delete /backup/ /recover/",
-        ]
+    cp = run(
+        ["docker", "volume", "inspect", "--format", "{{ .Mountpoint }}", volume_name],
+        capture=True,
     )
+    raw = cp.stdout or b""
+    mountpoint = (raw.decode() if isinstance(raw, bytes) else raw).strip()
+    if not mountpoint:
+        print(
+            f"ERROR: could not resolve mountpoint for volume {volume_name}",
+            file=sys.stderr,
+        )
+        return 2
+
+    src = os.path.join(backup_files_dir, "")
+    dest = os.path.join(mountpoint, "")
+    run(["rsync", "-avv", "--delete", src, dest])
     print("File restore complete.")
     return 0