RastaConverter1.0-RC3

• Added experimental ANTIC 4 character-mode output. Select it in the Live UI
  or with /graphics_mode=antic4; ANTIC E remains the default.
• ANTIC 4 uses a 168-colour-clock wide playfield and optimizes all five
  playfield colours, with each 4x8 cell selecting COLPF2 or COLPF3 for its
  fourth colour. Heights are complete 8-scanline character rows from 8 to 240.
• Added hardware-aware ANTIC 4 scheduling for LMS badlines, ordinary badlines,
  continuation lines, deferred refresh, and CHBASE transitions. The timing
  model and randomized five-seed differential suite reproduce Altirra output
  exactly.
• Added complete ANTIC 4 export: padded screen data, packed character sets,
  PMG data, raster programs, optimizer state, and a dedicated MADS template.
  The Recent view recognizes text-mode runs and its XEX action assembles them.
• Added GUI support throughout setup, preview, copied command lines, recent-run
  badges, and XEX freshness detection. Dual-frame controls are disabled because
  ANTIC 4 is currently single-frame only.
• The in-conversion viewer now hides its Mask display controls when no details
  mask is active, while retaining the neutral layer needed to start live
  painting.
• Preserved the ANTIC E code path and merged the RC2 portability fixes. Unit
  tests, ANTIC E and ANTIC 4 conversion smoke tests, and ANTIC 4 XEX assembly
  all pass after integration.
• Removed an accidentally committed Python bytecode cache and corrected the
  ANTIC 4 proof tool to use the released wide-playfield timing schedule.