Add backend support for the typing game: curriculum, progress, and reward unlocks

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>

python-backend/config.yml.example

@@ -118,6 +118,16 @@ general:
       - entity_id: scene.kinderzimmer_gute_nacht
         name: "Gute Nacht"
 
+  # The typing game ("Tippen"). Omit the whole section to hide its tab in the web
+  # front-end. The lesson plan is content, not device config, so it lives in its own
+  # file - see tippen-curriculum.yml.example for the format, including the optional
+  # `unlocks:` key that turns passing a lesson into unlocking part of the library.
+  tippen:
+    curriculum_file: tippen-curriculum.yml
+    # Where progress (stars, unlocked lessons, streak, ...) is saved. Written by the
+    # app itself - never hand-edited. Relative to this file, like curriculum_file.
+    progress_file: tippen-progress.json
+
 # One entry per figurine. The key is the figure name and the subfolder name.
 figures:
   fuchs: