fix: address Copilot review feedback on bash scripts

- Add jq compact mode (-c) to preserve single-line JSON output
- Use has_jq() from common.sh instead of inline command -v jq
- Shell-escape BRANCH_NAME with printf '%q' in persistence hint

Author: pierluigilenoci

scripts/bash/check-prerequisites.sh

@@ -89,7 +89,7 @@ if $PATHS_ONLY; then
     if $JSON_MODE; then
         # Minimal JSON paths payload (no validation performed)
         if has_jq; then
-            jq -n \
+            jq -cn \
                 --arg repo_root "$REPO_ROOT" \
                 --arg branch "$CURRENT_BRANCH" \
                 --arg feature_dir "$FEATURE_DIR" \
@@ -160,7 +160,7 @@ if $JSON_MODE; then
         else
             json_docs=$(printf '%s\n' "${docs[@]}" | jq -R . | jq -s .)
         fi
-        jq -n \
+        jq -cn \
             --arg feature_dir "$FEATURE_DIR" \
             --argjson docs "$json_docs" \
             '{FEATURE_DIR:$feature_dir,AVAILABLE_DOCS:$docs}'

scripts/bash/create-new-feature.sh

@@ -301,11 +301,11 @@ SPEC_FILE="$FEATURE_DIR/spec.md"
 if [ -f "$TEMPLATE" ]; then cp "$TEMPLATE" "$SPEC_FILE"; else touch "$SPEC_FILE"; fi
 
 # Inform the user how to persist the feature variable in their own shell
-echo "# To persist: export SPECIFY_FEATURE=$BRANCH_NAME" >&2
+printf '# To persist: export SPECIFY_FEATURE=%q\n' "$BRANCH_NAME" >&2
 
 if $JSON_MODE; then
-    if command -v jq >/dev/null 2>&1; then
-        jq -n \
+    if has_jq; then
+        jq -cn \
             --arg branch_name "$BRANCH_NAME" \
             --arg spec_file "$SPEC_FILE" \
             --arg feature_num "$FEATURE_NUM" \

scripts/bash/setup-plan.sh

@@ -52,7 +52,7 @@ fi
 # Output results
 if $JSON_MODE; then
     if has_jq; then
-        jq -n \
+        jq -cn \
             --arg feature_spec "$FEATURE_SPEC" \
             --arg impl_plan "$IMPL_PLAN" \
             --arg specs_dir "$FEATURE_DIR" \