fix(ingest): serialize ingests + fix scan-all REPOS_DIR path leak

scan-all.sh: `/var$REPOS_DIR` concatenated a literal `/var` prefix,
producing `/var$REPOS_DIR` when REPOS_DIR was unset. Replace with a
proper guard: use REPOS_DIR only when it is non-empty and points to an
existing directory.

ingest.yml: concurrent repository_dispatch deliveries race on the
commit+push; one writer loses. Add a concurrency group
(cancel-in-progress: false) to queue them instead.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/ingest.yml

@@ -17,6 +17,12 @@ on:
 permissions:
   contents: write
 
+# Serialize ingests: concurrent repository_dispatch deliveries race on
+# the commit+push and one writer loses. Queue them instead.
+concurrency:
+  group: verisimdb-data-ingest
+  cancel-in-progress: false
+
 jobs:
   ingest:
     runs-on: ubuntu-latest

scripts/scan-all.sh

@@ -16,8 +16,9 @@ DEFAULT_REPOS=(
 )
 
 REPOS_TO_SCAN=("${@:-${DEFAULT_REPOS[@]}}")
-if [[ -d "/var$REPOS_DIR" ]]; then
-    REPOS_BASE="/var$REPOS_DIR"
+# REPOS_DIR (if set) must be an absolute path to the repo collection.
+if [[ -n "${REPOS_DIR:-}" && -d "${REPOS_DIR}" ]]; then
+    REPOS_BASE="${REPOS_DIR}"
 else
     REPOS_BASE="$HOME/Documents/hyperpolymath-repos"
 fi