fix: bug: dev-agent does not clean up branch/worktree on CI exhausted or block (#115)

lib/pr-lifecycle.sh

@@ -348,6 +348,22 @@ pr_is_merged() {
   [ "$merged" = "true" ]
 }
 
+# ---------------------------------------------------------------------------
+# pr_close — Close a PR via forge API.
+# Args: pr_number
+# Returns: 0=closed, 1=error
+# ---------------------------------------------------------------------------
+pr_close() {
+  local pr_num="$1"
+
+  _prl_log "closing PR #${pr_num}"
+  curl -sf -X PATCH \
+    -H "Authorization: token ${FORGE_TOKEN}" \
+    -H "Content-Type: application/json" \
+    "${FORGE_API}/pulls/${pr_num}" \
+    -d '{"state":"closed"}' >/dev/null 2>&1 || true
+}
+
 # ---------------------------------------------------------------------------
 # pr_walk_to_merge — Walk a PR through CI, review, and merge.
 #