Moves the imported `mongo-container` project off Poetry and onto the repo's bazel/uv toolchain.

• *uv:* `release-container/pyproject.toml` is now PEP 621 with `uv.lock`; `poetry.lock` and `setup.cfg` are removed. `[tool.uv] constraint-dependencies` pins `pydantic<2` and `urllib3==1.26.15`, and `requests<2.32` is capped because `docker==6.0.1` fails on newer `requests` ("Not supported URL scheme http+docker"). Unused deps (jsonschema, psutil, pyjwt, cryptography, flake8/black/isort/mypy plugins, pipx) are dropped.
• *Bazel:* a second pycross hub, `@release_container_pypi`, reads `release-container/uv.lock` (`MODULE.bazel`). `bazel/uv/defs.bzl` `dependency()` takes an optional `hub`. `release-container/BUILD.bazel` adds a `scripts` library, py_binaries for the CLIs, and three py_tests. `release-container` is removed from `.bazelignore`.
• *Scripts/docs:* `create_python_venv.sh` installs uv 0.11.13 and runs `uv sync --locked`; `poetry run` is replaced by `uv run --locked`; the README setup section is rewritten.
• *Lint:* ruff lint fixes applied to `release-container/`.