PRCXI9300Deck now accepts model="9300"|"9320" to auto-select 6-slot or
16-slot layout. DefaultLayout gains default_layout for 9300 with T6 as
trash. PRCXI9300Handler auto-derives is_9320 from deck.model when not
explicitly passed. Includes 9300 slim experiment JSON and test fixes.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>