store: add NoPayStation source (PSP + PS1 Classics .pkg)

New 'NoPayStation' option in the Store tab lists PSP_GAMES.tsv and
PSX_GAMES.tsv, downloads each item's encrypted .pkg and decrypts/extracts
it with pkg2zip into a configurable output dir (<dir>/PSP/<TITLE_ID>/ and
<dir>/PSX/<TITLE_ID>/). Downloaded PSP games and PS1 Classics appear in the
Library (games/eboot and ps1/eboot respectively) and copy to the PSP as
PSP/GAME folders.

- app/nopaystation.py: TSV fetch/parse (cached) + pkg2zip discovery/extract.
- app/transfers.py: NoPayStationSource (scan + download).
- Settings: NPS output dir + pkg2zip path (QSettings nps_dir/pkg2zip_path).
- StorePage: NPS source + content-type combo (PSP Games / PS1 Classics),
  per-item cover system, TSV release dates, nps-download job kind.
- Library: _nps_library_items ingest, on-PSP detection, folder copy/delete,
  PPSSPP play disabled for encrypted PSP EBOOTs.
- README: document the source, pkg2zip + npdrm_free requirements.

app/transfers.py

@@ -463,3 +463,49 @@ class LocalShareSource(Source):
             return dest
         finally:
             shutil.rmtree(tmp, ignore_errors=True)
+
+
+class NoPayStationSource(Source):
+    """Browse NoPayStation .pkg lists and install PSP/PSX PSN content.
+
+    ``content_type`` is ``"psp"`` (PSP_GAMES.tsv) or ``"psx"`` (PSX_GAMES.tsv).
+    Downloading decrypts the ``.pkg`` with the ``pkg2zip`` binary and writes a
+    ``<TITLE_ID>/EBOOT.PBP`` game folder into ``dest_dir``.
+    """
+
+    label = "NoPayStation"
+
+    def __init__(self, content_type, tsv_url="", pkg2zip_path=""):
+        from . import nopaystation
+        self.content_type = content_type
+        self.tsv_url = tsv_url or nopaystation.tsv_url(content_type)
+        self.pkg2zip = pkg2zip_path or ""
+
+    def scan(self, root=None):
+        from . import nopaystation
+        return nopaystation.fetch_items(self.content_type, self.tsv_url)
+
+    def download(self, item, dest_dir, progress_cb=None, cancel_event=None):
+        from . import nopaystation
+        dest_dir = Path(dest_dir)
+        dest_dir.mkdir(parents=True, exist_ok=True)
+
+        pkg2zip = nopaystation.find_pkg2zip(self.pkg2zip)
+        if pkg2zip is None:
+            raise RuntimeError(
+                "pkg2zip not found — install it (https://github.com/mmozeiko/pkg2zip) "
+                "or set its path in Settings → Store."
+            )
+        title_id = item.get("title_id") or item.get("content_id") or ""
+        pkg_name = re.sub(r"[^A-Za-z0-9_-]", "", title_id) or "pkg"
+        tmp = Path(tempfile.mkdtemp(prefix="nps-download-"))
+        pkg = tmp / f"{pkg_name}.pkg"
+        try:
+            if progress_cb is not None:
+                progress_cb("Downloading", 0.0, "")
+            download_url(item["pkg_url"], pkg, None, progress_cb, cancel_event)
+            folder = nopaystation.extract_pkg(pkg, title_id, dest_dir, pkg2zip,
+                                              progress_cb, cancel_event)
+            return folder
+        finally:
+            shutil.rmtree(tmp, ignore_errors=True)