ignore local fc-eval runs/ output

Author: atharvas

.gitignore

@@ -20,4 +20,7 @@ CLAUDE.md
 # main www deploy can serve formulacode.org/docs/{eval,data} without a
 # Python toolchain in CI. Refresh with `make docs` (see Makefile).
 _repos/
-.venv-docs/
+.venv-docs/
+
+# Local fc-eval run output (created by `fc-eval run` from this directory).
+runs/