Fix onboard import cloning from empty new repo instead of archived repo

initial_import() now accepts an optional clone URL override parameter.
onboard_flow() passes the archived repo URL so content is cloned from
the right source.

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

lib/sync.sh

@@ -200,9 +200,13 @@ reverse_sync() {
 #
 # Used when a subrepo already has content and you're adding it to the
 # monorepo for the first time. Creates a PR.
+# Usage: initial_import [clone_url_override]
+#   clone_url_override — if set, clone from this URL instead of subrepo_auth_url()
+#                        (used by onboard to clone from the archived repo)
 # Returns: skip | pr-created
 
 initial_import() {
+  local clone_url="${1:-$(subrepo_auth_url)}"
   local mono_branch="$SYNC_BRANCH_MONO"
   local subrepo_branch="$SYNC_BRANCH_SUBREPO"
   local subfolder
@@ -225,8 +229,8 @@ initial_import() {
     --branch "$mono_branch" --single-branch \
     "${work_dir}/monorepo" || die "Failed to clone monorepo"
 
-  # 2. Clone subrepo
-  git clone "$(subrepo_auth_url)" \
+  # 2. Clone subrepo (or archived repo when clone_url is overridden)
+  git clone "$clone_url" \
     --branch "$subrepo_branch" --single-branch \
     "${work_dir}/subrepo" || die "Failed to clone subrepo"