Merge pull request #1 from denizsincar29/copilot/create-md-file-for-features

Enable oldschool dkm sounds for keyboard typing, skip dkm for word spaces

Fix oldschool dkm sounds for text-to-morse, hide download audio button, improve word spacing

Fix Russian period, word space playback, audio download filename, and remove oldschool dkm sounds

Remove letter announcement and scheduler functionality

Replace ё with е in decoded Russian morse text

Fix letter announcement timing and exercise auto-advance

Fix multiple bugs: WPM save, letter announcement timing, exercise flow, remove decoder button, remove dropdown announcements, improve scheduler

Fix k-means pause clustering with dot-duration-based guide pauses

Fix synth audio overlap and redesign exercise with continuous feedback

Fix word space recognition in k-means decoder

Fix keyboard typing overlap and k-means single word decoding

Fix bugs: telegraph/oldschool WPM, modal closing, Russian punctuation, oldschool sounds, decoder in realtime

Add implementation summary documentation

Implement complete web PWA with all features