Title metadata for the library view

Cheaper than recorded - see D055. sce_sys/param.json is plain JSON and sce_sys/icon0.png a plain PNG, so real names and icons cost a serde_json call and an image load, not a parser. D040 assumed filenames-first on cost grounds that turned out not to apply, so this is worth pulling into the phase 2b GUI shell rather than deferring.