A lesson's `keys` was capped at two outright, which made it impossible to write
"K, with the four keys before it still in play". The cap now counts only what is
*new*; keys already taught can be listed freely, and the spotlight falls on the
new ones alone, so a lesson titled "K" drills K instead of spreading itself
evenly over all five keys it names. A round that introduces nothing new still
spotlights its whole list - that is the "mixed" replay, unchanged.
Also documents `unlocks:` paths as relative to the library root. Absolute and
"~" paths still resolve, so an existing file keeps working, but a relative path
survives moving the library.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Moves the typing app's lesson plan and progress from client-side YAML/localStorage
into the backend, and adds a reward system that ties passing a lesson to unlocking
part of the music library. Lock state is always recomputed live from curriculum x
progress x the live library, never persisted separately.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
