Add Docker, migrations, and initial database setup

Added Dockerfile and docker-compose.yaml for containerization. Introduced Alembic migrations with initial schema and a migration to alter column types. Added requirements.txt for dependencies and removed temp.py cleanup script. Updated .gitignore to allow tracking of migration files.

docker-compose.yaml

@@ -0,0 +1,9 @@
+version: "3.9"
+services:
+  app:
+    build: .
+    container_name: my_python_sqlite_app
+    ports:
+      - "5000:5000"  # change if needed
+    volumes:
+      - ./data:/app/data  # maps host ./data to container /app/data