fix(check-manifests): skip remote-sourced plugins in local path check

## Why
The hook was treating all source values as local directory paths. Remote
sources (github/git/npm objects) have no local directory — the jq -r of
a JSON object produced garbage, causing the hook to fail on push after
adding the mattpocock-skills remote plugin.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/check-manifests.sh

@@ -23,6 +23,13 @@ plugin_count=$(jq '.plugins | length' "$MARKETPLACE")
 
 for ((i = 0; i < plugin_count; i++)); do
   name=$(jq -r ".plugins[$i].name" "$MARKETPLACE")
+  source_type=$(jq -r ".plugins[$i].source | type" "$MARKETPLACE")
+
+  # Remote sources (github, git, npm objects) have no local directory to check
+  if [[ "$source_type" != "string" ]]; then
+    continue
+  fi
+
   source=$(jq -r ".plugins[$i].source" "$MARKETPLACE")
   source="${source#./}"
   plugin_dir="$REPO_ROOT/$source"