Use 'timefold' (not 'timefold-solver') and revert to ARM platform

The Python distribution is published on PyPI as 'timefold' — only the
Java module is called 'timefold-solver'. With the correct package the
ARM64 wheel resolves cleanly, so revert the linux/amd64 workaround.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -302,10 +302,7 @@ services:
       context: ./timetable-solver-service
       dockerfile: Dockerfile
     container_name: bp-lehrer-timetable-solver
-    # timefold-solver only ships x86_64 wheels — emulate via Rosetta on
+    platform: linux/arm64
-    # the ARM Mac Mini. Cloud target (memory says cloud OK for this svc)
-    # would be linux/amd64 native.
-    platform: linux/amd64
     ports:
       - "8095:8095"
     environment:

timetable-solver-service/requirements.txt

@@ -3,6 +3,6 @@ uvicorn[standard]==0.32.0
 asyncpg==0.30.0
 pydantic==2.9.2
 pydantic-settings==2.6.0
-timefold-solver==1.21.1
+timefold==1.24.0b0
 httpx==0.27.2
 python-multipart==0.0.12