fix: 30min wall-clock timeout on backup subprocess + global padding-top on .fc-content so views don't start under the sticky TopNav

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/services/migrators/backup.py

@@ -37,12 +37,21 @@ def _backups_dir(images_root: Path | None = None) -> Path:
     return p
 
 
+_DEFAULT_SUBPROCESS_TIMEOUT_S = 30 * 60  # 30 minutes
+
+
 def _run_subprocess(cmd: list[str], **kwargs: Any):
-    # Overridable for tests via monkeypatch.
+    # Overridable for tests via monkeypatch. Hard wall-clock timeout
+    # guards against pg_dump / tar / zstd hangs on NFS — without it the
+    # task pretends to be 'running' forever (operator hit this 2026-05-
+    # 23 with two backups stuck in MigrationRun). On timeout
+    # subprocess.run raises TimeoutExpired which the caller surfaces as
+    # a task error.
     return subprocess.run(
         cmd,
         capture_output=True,
         check=True,
+        timeout=_DEFAULT_SUBPROCESS_TIMEOUT_S,
         **{k: v for k, v in kwargs.items() if not k.startswith("_")},
     )