fix: resolve per-torrent qb save paths

docs/storage-safety.md

@@ -14,6 +14,13 @@ client:
    a regular file or an explicitly created directory;
 5. verifies every operation remains beneath the local configured root.
 
+For qBittorrent content, the root is resolved per resource: qB's authoritative
+API-visible `save_path` is mapped beneath `qbittorrent.api_root` (or a more
+specific configured local override) into the client namespace. This permits
+existing nested save paths without moving data, but does not permit paths
+outside the configured boundary. The resolved path remains local client state
+and is never sent to the control daemon.
+
 Sockets, devices, FIFOs, symlinks, and other special entries fail preflight.
 Permission or ownership mismatch is fail-fast. Archive Control never changes
 source ownership or mode to make a job pass.
@@ -150,4 +157,3 @@ Offline tooling provides list, verify, and restore. Restore requires stopped
 daemon access, verifies the chosen backup, preserves the suspect database under
 a timestamped name, installs the replacement atomically, and runs integrity and
 schema checks before normal startup. Backups contain no configured secrets.
-