Unbundle covers: fetch psppt-covers.zip from repo on demand with user prompt

psppt.spec

@@ -1,8 +1,8 @@
 # -*- mode: python ; coding: utf-8 -*-
 """PyInstaller spec: build psppt (onedir).
 
-Bundles the read-only resources (DATs, PS1 loader, offline cover bundles,
-icons) under ``lib/`` next to the executable. User-writable data
+Bundles the read-only resources (DATs, PS1 loader, cover templates, index
+catalogs, icons) under ``lib/`` next to the executable. User-writable data
 (credentials, manual covers, PS1 templates, NPS cache, library DB, cover
 cache) lives in the OS state dir at runtime — see ``app/config.py``.
 
@@ -15,8 +15,6 @@ datas = [
     ("data/dats", "data/dats"),
     ("data/loader", "data/loader"),
     ("data/supplement.json", "data"),
-    ("data/covers/libretro-covers.zip", "data/covers"),
-    ("data/covers/openvgdb-covers.zip", "data/covers"),
     ("data/covers/libretro-index.json", "data/covers"),
     ("data/covers/openvgdb-index.json", "data/covers"),
     ("data/covers/UMD_COVER_TEMPLATE.png", "data/covers"),