Move Docker files to docker/ directory

- Move Dockerfile, Dockerfile.base, docker-compose.yml to docker/
- Update docker-compose.yml with correct context paths
- Update scripts/build.sh to use new paths
- Update DOCKER_QUICKSTART.md with new commands
- Add scripts/build.sh to tracked files

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitignore

@@ -70,6 +70,7 @@ scripts/*
 !scripts/smoke-test.sh
 !scripts/setup-trusted-certs.sh
 !scripts/screenshots.sh
+!scripts/build.sh
 
 # Web UI auth database and SSL certs
 instance/