fix(pre_build): a fully-ignored dataset/ must not abort the release (#154)

`git add dataset/` exits non-zero when every path it matches is ignored,
and pre_build.sh runs under `set -e`, so the first workspace with a wholly
ignored dataset/ killed the release before anything was dispatched.

7 of 11 release workspaces ignore dataset/ outright (autofit_workspace, the
three *_workspace_test repos, and the three HowTo repos), so this aborted on
the very first repo processed. Staging nothing is the correct outcome there.

Latent since #150 dropped the `git add -f` (correctly — the -f was force-
committing simulated datasets, #126). The live path has not run since: the
2026.7.9.1 release predates #150, and the nightly driver has stopped at
Stage 4 validation every night since, so this is the first execution of the
step post-#150.

Only the failure path changes: where `git add dataset/` already succeeded
(autolens_workspace's 13 allowlisted real datasets, autogalaxy_workspace's 5)
the command is unchanged and real observational data still stages.

Co-authored-by: Jammy2211 <JNightingale2211@gmail.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: 3 people

pre_build.sh

@@ -72,7 +72,12 @@ run_workspace() {
     # `git add -f` here force-committed simulated datasets that are meant to be
     # generated at runtime via al.util.dataset.should_simulate(); only allowlisted
     # real data may be staged. See PyAutoBuild#126.
-    [ -d dataset ] && git add dataset/
+    # A fully-ignored dataset/ is the normal case, not an error: git add exits
+    # non-zero when every path it matches is ignored, and under `set -e` that
+    # aborts the whole release. Staging nothing is the correct outcome there.
+    if [ -d dataset ]; then
+        git add dataset/ 2>/dev/null || true
+    fi
     for d in config notebooks scripts; do
         [ -d "$d" ] && git add "$d/"
     done