PanDDA2 1.0.0: new module, uv venv from sha-pinned xchem/PanDDA2

Separate module from PanDDA (different library): self-contained python 3.9
venv (torch==1.13.1 caps at py3.10), torch from the pytorch CPU wheel index,
~1 GB of CNN scoring models pre-fetched at build time because the package dir
is read-only for users under /opt/psi. ccp4/9.0 runtime dep only, for
pandda.inspect / pandda.export.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0152MuuYUaapP7CtxrDAfvBh

PanDDA2/README.md

@@ -0,0 +1,28 @@
+# PanDDA2
+
+PanDDA 2 (`pandda_2_gemmi`) — multi-dataset density analysis for fragment
+screening. <https://github.com/xchem/PanDDA2>
+
+Not on PyPI: installed with uv into a self-contained python 3.9 venv from a
+sha-pinned commit of xchem/PanDDA2 master (no usable release tags upstream;
+module version 1.0.0 follows the README's announced version — bump the sha in
+`build` to update). Torch comes from the pytorch CPU wheel index to avoid the
+~2 GB CUDA build.
+
+The ~1 GB of CNN scoring models that PanDDA2 normally gdown-fetches on first
+run are downloaded at build time into the installed package dir, because that
+dir is read-only for users under /opt/psi. If Ra blocks Google Drive, download
+the 5 files by hand (ids in `build`) and copy them into the dir named in the
+die message.
+
+ccp4/9.0 is a runtime dependency (auto-loaded) for `pandda.inspect` /
+`pandda.export`. The build needs no ccp4 — the venv is self-contained.
+Upstream README claims inspect/export "do not function correctly" outside
+ccp4/7.0.067; verify with 9.0 before trusting exports.
+
+Verify after load:
+
+```bash
+pandda2.analyse --help
+$PANDDA2_ENV/bin/python -c 'from pandda_gemmi.cnn import LitEventScoring'
+```