This PR changes the `kubernetes` and `machine` profiles of `charmcraft init` to use the tox-uv plugin (for testing) and the uv Charmcraft plugin (for packing). [Here's a minimal Kubernetes charm generated from the updated profiles](https://github.com/dwilding/vm/tree/main/demo-api-charm) ### Profile changes - Dependencies are now listed in *pyproject.toml*. I've removed *requirements.txt*. - The environments in *tox.ini* now require uv. The user should install tox with `uv tool install tox --with tox-uv`. - The scope of `tox -e static` now includes *tests/unit/* and *tests/integration/* for the charms. Strictly, this isn't part of switching to uv. - *uv.lock* is provided as part of the profiles. (We went back and forth on this in discussions.) But the file is **not** generated using `uv lock`. The Charm Tech team will periodically refresh the *uv.lock.j2* templates to keep up with major Ops features or dependency issues. - *charmcraft.yaml* now specifies the uv plugin. After discussion (in the comments of this PR), I felt it's best not to have a dedicated dependency group for PYDEPS from charmlibs. - Misc cleanup: I updated some old links to Juju docs and adjusted the formatting of *charmcraft.yaml* to avoid double blank lines. ### Help & doc changes - Modified the help output of `charmcraft init` to: - Explain that *pyproject.toml* specifies dependencies if the profile is `kubernetes` or `machine` - Explain that *requirements.txt* is created for 12-factor profiles only - List *uv.lock* and say that this file is created for `kubernetes` and `machine` - Updated the following docs (links to previews): - [pyproject.toml file](https://canonical-charmcraft--2312.com.readthedocs.build/2312/reference/files/pyproject-toml-file/) - [requirements.txt file](https://canonical-charmcraft--2312.com.readthedocs.build/2312/reference/files/requirements-txt-file/) - [tox.ini file](https://canonical-charmcraft--2312.com.readthedocs.build/2312/reference/files/tox-ini-file/) - [uv.lock file](https://canonical-charmcraft--2312.com.readthedocs.build/2312/reference/files/uv-lock-file/) (new) - Removed [requirements-dev.txt file](https://canonical-charmcraft.readthedocs-hosted.com/stable/reference/files/requirements-dev-txt-file/) because it doesn't seem to be referenced anywhere and I can't find any Charmcraft code that creates/uses this file. I've redirected the page to [requirements.txt file](https://canonical-charmcraft--2312.com.readthedocs.build/2312/reference/files/requirements-txt-file/). --- Follow-up actions: - Expand docs about the uv plugin - see https://github.com/canonical/charmcraft/issues/2238#issuecomment-2900521717 - After the profile changes are released, https://github.com/canonical/operator/issues/1742