fix: make overlay dep grep non-fatal under pipefail (#281)

[jeremylongshore]

Fixes #281.

services/api/entrypoint.sh runs under set -euo pipefail. When an overlay tool dir exists but yields zero pip deps, _extra_deps is just a newline, so the [[ -n "${_extra_deps}" ]] guard passes but grep -v '^$' matches nothing and exits 1. With no || true, the script aborts before exec "$@" and the api pod CrashLoopBackOffs with empty logs.

One-line guard on the grep, as suggested in the issue:

-    echo "$_extra_deps" | sort -u | grep -v '^$' > /tmp/_extra_deps.txt
+    echo "$_extra_deps" | sort -u | grep -v '^$' > /tmp/_extra_deps.txt || true

No effect on the success path: with real deps grep exits 0 and the guard is a no-op; with none, the empty file is already handled by the guarded uv pip install -r ... || true on the next line.

Tested: shellcheck clean, bash -n ok, and an isolated repro of the fragment crashes before / passes after. I couldn't run the full overlay-mount path end-to-end without the cluster.