Replace the YAML exercise catalogs with the motion-rig exercise library

The exercise picker now lists the bundled exercise library — the
motion-rig exercises exported from Exercise Library/ — instead of the
two *.exercises.yaml starter catalogs. ExerciseListLoader and the Yams
dependency are removed; ExerciseMotionLibrary gains exerciseNames, the
bundle enumeration the picker reads.

project.yml

@@ -22,9 +22,6 @@ packages:
   IndieSync:
     url: https://git.rzen.dev/rzen/indie-sync.git
     from: "0.3.0"
-  Yams:
-    url: https://github.com/jpsim/Yams
-    from: "6.0.0"
 
 targets:
   # ---- iOS app (owns iCloud Drive sync; embeds the watch app) ----------------
@@ -49,7 +46,6 @@ targets:
     dependencies:
       - package: IndieAbout
       - package: IndieSync
-      - package: Yams
       - target: Workouts Watch App
     postBuildScripts:
       - script: '"${SRCROOT}/../indie-skills/skills/app-versioning/scripts/update_build_info.sh"'