GameInfoCache: report the firmware updater bundled on a game disc

Adds GameInfoFlags::BUNDLED_UPDATE_INFO, holding the version, title, size
and timestamp of the updater in PSP_GAME/SYSDIR/UPDATE. It comes from the
PARAM.SFO and the directory entry next to the archive, so it's a couple of
small reads on the ISOFileSystem the worker already has open - no
decryption, and DATA.BIN itself is only sniffed for its magic. Only
computed for ISOs; everything else is marked complete with an empty struct.

ISOFileSystem now parses the date out of the ISO9660 directory record,
stored as Unix UTC seconds and reported as the PSP's atime/ctime/mtime.
Those used to always read back as zero, so games calling sceIoGetstat on a
UMD file saw 1900 where hardware gives the mastering date.

Shown on GameScreen as e.g. "Firmware update on disc: 6.60 (2011-10-05),
25.6 MB".

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0149QcTVgZEXKXbgHyvXF4ZY

UI/GameInfoCache.cpp

@@ -851,6 +851,15 @@ handleELF:
 					}
 				}
 
+				// Most UMDs carry a firmware updater, which is a source of things like the
+				// system fonts. Just note down what's there - unpacking it is a separate step.
+				if (flags_ & GameInfoFlags::BUNDLED_UPDATE_INFO) {
+					BundledUpdateInfo update;
+					ReadBundledUpdateInfo(&umd, "/", &update);
+					std::lock_guard<std::mutex> lock(info_->lock);
+					info_->bundledUpdate = update;
+				}
+
 				if (flags_ & GameInfoFlags::PIC0) {
 					info_->pic0.dataLoaded = ReadFileToString(&umd, join(gameRoot, "PIC0.PNG"), &info_->pic0.data, &info_->lock);
 				}