fix: record each platform's own list version

install/<platform>.json wrote the constant "1.0" as the version of the
list it was built from. The manifest now carries the version the platform
YAML records, and generate_pack refuses a YAML without one.

inherits: no longer passes a parent's version to a child: Lakka was
published as RetroArch v1.22.2 in its manifest, pack name and site page.
lakka.yml records v6.1, the Lakka-LibreELEC tag its target list is read
at. The MiSTer scraper refuses a BiosDB without a timestamp instead of
writing an empty version.

A pack's manifest.json records list_version, so an install from the pack
alone knows it too. Manifests regenerated twice and compared: only
version and generated changed.

tests/test_minui_platform.py

@@ -193,6 +193,7 @@ class PackPlacesCoreFilesUnderTheTag(unittest.TestCase):
 
         platform = {
             "platform": "MinUI Test",
+            "version": "2025-11-27",
             "base_destination": "",
             "verification_mode": "existence",
             "cores": ["gambatte", "arcadecore", "unlisted"],