fix: resolve per-torrent qb save paths

tests/test_config.py

@@ -78,6 +78,35 @@ class ConfigTests(unittest.TestCase):
             Path("/local/qb/Sync"),
         )
 
+    def test_qbittorrent_can_override_a_nested_save_path(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            for name in ("token", "qb-password", "syncthing-key"):
+                path = root / name
+                path.write_text(name, encoding="utf-8")
+                os.chmod(path, 0o600)
+            (root / "qb").mkdir()
+            (root / "fast").mkdir()
+            (root / "sync").mkdir()
+            config_path = root / "client.toml"
+            config_path.write_text(
+                _config(root).replace(
+                    f'local_root = "{root / "qb"}"',
+                    f'local_root = "{root / "qb"}"\n'
+                    "local_path_overrides = { \"/downloads/fast\" = "
+                    f'"{root / "fast"}" }}',
+                    1,
+                ),
+                encoding="utf-8",
+            )
+            config = ClientConfig.load(config_path)
+            self.assertEqual(
+                config.qbittorrent.roots.api_to_local(
+                    "/downloads/fast/resource/file.bin"
+                ),
+                root / "fast/resource/file.bin",
+            )
+
     def test_endpoint_scheme_and_job_keys_are_strict(self):
         with tempfile.TemporaryDirectory() as directory:
             root = Path(directory)