crystfel: default uv to /usr/bin/uv (system package on Ra)

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

crystfel/README.md

@@ -22,7 +22,7 @@ too old and the system python is 3.9 (EOL, meson >= 1.12 needs >= 3.10).
 `uv sync --locked` into a throwaway venv in the build scratch dir, on a
 uv-managed Python 3.12 (downloaded on first use, also into scratch). Nothing of
 this lands in `$PREFIX`. `uv` must be on the build host (default
-`~/.local/bin/uv`, `pip3 install --user uv`; override with `UV=/path/to/uv`).
+`/usr/bin/uv`; override with `UV=/path/to/uv`).
 Wheel cache is the shared `/opt/psi/MX/.uv-cache` (home quota).
 
 **HDF5 is bundled.** The Ra build node has no `hdf5-devel`, no `h5cc` and no

crystfel/build

@@ -20,8 +20,8 @@
 # wrong cwd silently builds nothing (modbuild has no errexit in hooks).
 
 crystfel::env() {
-    # modbuild's shell strips ~/.local/bin from PATH; override with UV=/path/to/uv if needed
-    UV="${UV:-$HOME/.local/bin/uv}"
+    # system uv on Ra; override with UV=/path/to/uv if needed
+    UV="${UV:-/usr/bin/uv}"
     # ~/.cache/uv hits the home disk quota; shared cache reuses wheels across MX builds
     export UV_CACHE_DIR="/opt/psi/MX/.uv-cache"
     export UV_PROJECT_ENVIRONMENT="${SRC_DIR}/../meson-venv"
@@ -33,7 +33,7 @@ crystfel::env() {
 
 pbuild::configure() {
     crystfel::env
-    [[ -x "$UV" ]] || std::die 42 "uv not found at $UV - run: pip3 install --user uv  (or set UV=/path/to/uv)"
+    [[ -x "$UV" ]] || std::die 42 "uv not found at $UV - dnf install uv, or set UV=/path/to/uv"
     for t in flex bison make; do
         command -v "$t" >/dev/null || std::die 42 "$t not on PATH - crystfel/hdf5 need it (dnf install $t)"
     done