The go-sixel library panics on certain image dimensions during Resize().
Added panic recovery in drawImage() that falls back to alt text display.
Cleaned up all debug logging from the investigation.
- Decode images in background goroutine, not in Draw()
- Show [loading image...] placeholder until decode completes
- Skip pv.term.Draw() when composite is active (pager got no input)
- Thread-safe access to decoded image cache via sync.Mutex
- Invalidate callback triggers redraw when images finish decoding
Composite mode now handles j/k/g/G/PgUp/PgDown/mouse wheel for scrolling.
Text uses the configured default style. Images render inline via Vaxis.
Emails without images still use the standard pager path.
Mortdecai