Add Python TrainSim with loop track map and physics.

FastAPI server, replaceable JSON config, tests, Dockerfile.
Pairs with ATO via spec/interface.md contract.

Co-authored-by: Cursor <cursoragent@cursor.com>

.forgejo/workflows/ci.yml

@@ -1,4 +1,4 @@
-name: CodeView CI
+name: CodeView TrainSim CI
 
 on:
   push:
@@ -7,28 +7,21 @@ on:
     branches: [main]
 
 jobs:
-  lint:
+  test:
     runs-on: docker
+    container:
+      image: python:3.12-slim
     steps:
       - uses: actions/checkout@v4
-      - name: Lint
+      - name: Pytest
         run: |
-          if [ -f package.json ]; then npm ci && npm run lint; else echo "no lint configured"; fi
+          pip install -r requirements.txt
+          pytest -q
 
-  tests:
+  docker:
     runs-on: docker
-    needs: lint
-    steps:
-      - uses: actions/checkout@v4
-      - name: Unit tests
-        run: |
-          if [ -f package.json ]; then npm test; elif [ -f pyproject.toml ]; then pip install -e . && pytest; else echo "no tests configured"; fi
-
-  docker-build:
-    runs-on: docker
-    needs: tests
+    needs: test
     steps:
       - uses: actions/checkout@v4
       - name: Docker build
-        run: |
-          if [ -f Dockerfile ]; then docker build -t app:ci .; elif [ -f docker-compose.yml ]; then docker compose build; else echo "no docker build configured"; fi
+        run: docker build -t trainsim:ci .