careless: build venv with uv instead of conda (anaconda.com blocked on Ra)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

careless/README.md

@@ -8,17 +8,20 @@ inference (variational merging), built on TensorFlow.
 
 ## How it is built
 
-The build installs a private miniconda into `$PREFIX/miniconda`, creates a
-`careless_<version>` env with Python 3.12 (upstream supports >=3.9,<3.13),
-and runs `pip install careless[cuda]==<version>` inside it. The `[cuda]`
-extra pulls the NVIDIA libraries as pip wheels, so the same install works
-on GPU and CPU-only Ra nodes.
+Upstream recommends a fresh conda env, but repo.anaconda.com is not
+reachable from Ra, so the build uses uv instead: it fetches a standalone
+Python 3.12 into `$PREFIX/python` (upstream supports >=3.9,<3.13), creates
+`$PREFIX/venv`, and runs `uv pip install careless[cuda]==<version>` into
+it. The `[cuda]` extra pulls the NVIDIA libraries as pip wheels, so the
+same install works on GPU and CPU-only Ra nodes.
 
-Loading the module puts the env's `bin/` on `PATH` (the `careless` command
-is directly available, no `conda activate` needed) and sets `CARELESS_ENV`
-to the conda env path.
+`uv` must be on PATH on the build host (e.g. `pip install --user uv`).
+
+Loading the module puts the venv's `bin/` on `PATH` (the `careless`
+command is directly available, no activation needed) and sets
+`CARELESS_ENV` to the venv path.
 
 ## Adding a new version
 
 Add the version under `versions:` in `files/config.yaml`, then on a Ra
-login node: `./build <version>`.
+login node: `modbuild build <version>` (modbuild/2.1.2).