Finish SAND-WP-0002: remote smoke, podman-compose, HTTP stub

- T10 smoke passed on CoulombCore (sand-boxer self-deploy, sandbox 4e542c51)
- Add e2e smoke compose, scripts/smoke-compose-e2e.sh, make smoke-remote
- Support SANDBOXER_COMPOSE_CMD for podman-compose hosts
- FastAPI v0 stub at sandboxer.api.app; migration gaps doc
- Mark workplan finished (all 10 tasks done)

pyproject.toml

@@ -14,6 +14,7 @@ dependencies = [
     "pydantic>=2.0",
     "pyyaml>=6.0",
     "httpx>=0.27",
+    "fastapi>=0.115",
 ]
 
 [project.scripts]
@@ -39,4 +40,5 @@ select = ["E", "F", "I", "UP", "B", "SIM"]
 dev = [
     "pytest>=8.0",
     "ruff>=0.6",
+    "uvicorn[standard]>=0.32",
 ]