Fixes regression from #18546 and #18679.
## Problem
The is_from_yml ISO branch constructed iso_archive unconditionally,
bypassing the cache check inside add_game, making the cache write-only
for yml-sourced ISOs.
## Fix
Added a lightweight index cache entry (iso_path + "//index") storing the
subdir list + mtime. On hit, skips archive construction entirely. On
miss, walks as before and writes the index
Every launch constructs a fresh iso_archive for each ISO game, which
calls iso_form_hierarchy() and walks the full directory tree. On top of
that, qt_utils opens a second iso_archive just for icon loading, so
every ISO game ends up doing two full directory tree walks on every
launch.
This adds a metadata cache keyed by ISO path + mtime stored under
fs::get_config_dir()/iso_cache/. Each entry stores the raw SFO binary,
resolved icon/movie/audio paths and raw icon bytes.
- On cache hit, iso_archive construction is skipped entirely for both
game list scanning and icon loading
- On cache miss archive is scanned as before and the result is persisted
to disk
- Cache is automatically invalidated when the ISO file's mtime changes
Tested with a decrypted PS3 disc ISO (God of War III):
- First launch writes cache files correctly to iso_cache/
- Second launch reads from cache with correct title and icon
- touch game.iso correctly invalidates the cache and triggers a rescan
Megamouse
Vishrut Sachan