(docs) Add manual restore guidance for snapshots

Document the manual restore workflow in the README and surface snapshot-
specific restore commands on the snapshot detail page.

The guidance keeps restores intentionally manual for now: inspect the
snapshot data directory, run rsync with --dry-run, restore to staging
first, and treat hardlinked snapshot files as read-only.

src/pobsync_backend/templates/pobsync_backend/snapshot_detail.html

@@ -60,6 +60,38 @@
     </section>
   {% endif %}
 
+  <section class="panel">
+    <h2>Restore Guidance</h2>
+    <div class="stack spaced">
+      <div><strong>Snapshot data source:</strong> {{ restore.source_path }}</div>
+      <div><strong>Example staging destination:</strong> {{ restore.destination_path }}</div>
+      <div class="muted">
+        Restore from the snapshot's <code>data/</code> directory. Start with a dry run, restore to a staging path first,
+        and only then copy data back to a live host or service path.
+      </div>
+    </div>
+    <div class="stack spaced">
+      <div><strong>Inspect the snapshot:</strong></div>
+      <pre>{{ restore.inspect_command }}</pre>
+    </div>
+    <div class="stack spaced">
+      <div><strong>Dry-run restore to staging:</strong></div>
+      <pre>{{ restore.dry_run_command }}</pre>
+    </div>
+    <div class="stack spaced">
+      <div><strong>Restore to staging:</strong></div>
+      <pre>{{ restore.local_command }}</pre>
+    </div>
+    <div class="stack spaced">
+      <div><strong>Dry-run restore back to the source host:</strong></div>
+      <pre>{{ restore.remote_dry_run_command }}</pre>
+    </div>
+    <p class="muted">
+      Snapshots can contain hardlinks to files shared with earlier snapshots. Treat snapshot directories as read-only:
+      copy data out with rsync instead of editing files in place.
+    </p>
+  </section>
+
   <section class="panel">
     <h2>Backup Runs</h2>
     <table>

src/pobsync_backend/tests/test_views.py

@@ -1421,6 +1421,13 @@ class ViewTests(TestCase):
         self.assertContains(response, "Stats")
         self.assertContains(response, "Files seen:</strong> 100")
         self.assertContains(response, "Hardlinked files:</strong> 9")
+        self.assertContains(response, "Restore Guidance")
+        self.assertContains(response, f"{base.path}/data")
+        self.assertContains(response, f"/restore/{host.host}")
+        self.assertContains(response, "rsync -aHAX --numeric-ids --info=progress2 --dry-run")
+        self.assertContains(response, f"{base.path}/data/")
+        self.assertContains(response, "root@web-01.example.test:/")
+        self.assertContains(response, "Treat snapshot directories as read-only")
         self.assertContains(response, child.dirname)
         self.assertContains(response, f"Run {run.id}")
         self.assertContains(response, reverse("run_detail", args=[run.id]))

src/pobsync_backend/views.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import json
+import shlex
 import shutil
 import subprocess
 from pathlib import Path
@@ -494,12 +495,14 @@ def snapshot_detail(request, snapshot_id: int):
         SnapshotRecord.objects.select_related("host", "base").prefetch_related("derived_snapshots", "backup_runs"),
         id=snapshot_id,
     )
+    restore = _snapshot_restore_guidance(snapshot)
     context = {
         "snapshot": snapshot,
         "stats": snapshot.metadata.get("stats") if isinstance(snapshot.metadata, dict) else {},
         "metadata_json": _pretty_json(snapshot.metadata),
         "backup_runs": snapshot.backup_runs.select_related("host").order_by("-created_at"),
         "derived_snapshots": snapshot.derived_snapshots.select_related("host").order_by("-started_at", "dirname"),
+        "restore": restore,
     }
     return render(request, "pobsync_backend/snapshot_detail.html", context)
 
@@ -790,6 +793,28 @@ def _pretty_json(value: object) -> str:
     return json.dumps(value or {}, indent=2, sort_keys=True)
 
 
+def _snapshot_restore_guidance(snapshot: SnapshotRecord) -> dict[str, str]:
+    source_path = Path(snapshot.path) / "data"
+    destination_path = Path("/restore") / snapshot.host.host
+    quoted_source = _quote_path_with_trailing_slash(source_path)
+    quoted_destination = _quote_path_with_trailing_slash(destination_path)
+    quoted_remote_destination = shlex.quote(f"root@{snapshot.host.address or snapshot.host.host}:/")
+    common_args = "rsync -aHAX --numeric-ids --info=progress2"
+
+    return {
+        "source_path": str(source_path),
+        "destination_path": str(destination_path),
+        "inspect_command": f"ls -la {quoted_source}",
+        "dry_run_command": f"{common_args} --dry-run {quoted_source} {quoted_destination}",
+        "local_command": f"{common_args} {quoted_source} {quoted_destination}",
+        "remote_dry_run_command": f"{common_args} --dry-run {quoted_source} {quoted_remote_destination}",
+    }
+
+
+def _quote_path_with_trailing_slash(path: Path) -> str:
+    return shlex.quote(str(path).rstrip("/") + "/")
+
+
 def _run_rsync_log_path(run: BackupRun) -> Path | None:
     if isinstance(run.result, dict):
         log = run.result.get("log")