M8: Pre-compile regex once before rename preview loop instead of
recompiling per file. Adds apply_simple_compiled() to RenameConfig.
M9: Cache font data in watermark module using OnceLock (default font)
and Mutex<HashMap> (named fonts) to avoid repeated filesystem walks
during preview updates.
M12: Add 150ms debounce to watermark opacity, rotation, margin, and
scale sliders to avoid spawning preview threads on every pixel of
slider movement.
M13: Add 150ms debounce to compress per-format quality sliders (JPEG,
PNG, WebP, AVIF) for the same reason.
M14: Move thumbnail loading to background threads instead of blocking
the GTK main loop. Each thumbnail is decoded via image crate in a
spawned thread and delivered to the main thread via channel polling.
lashman
1a174d40a7