lib/strconv: add f64tos

.gitignore

@@ -28,6 +28,13 @@ lib/**/*.combined.ww
 examples/**/*.o
 examples/**/*.s
 examples/**/*.combined.ww
+
+# `test/wcc/data/` holds .ww fixtures fed to the C-side wcc tests
+# (e.g. attest_pass.ww). `ww build` against any of those drops the
+# usual triplet next to the source — only the .ww is tracked.
+test/wcc/data/*.o
+test/wcc/data/*.s
+test/wcc/data/*.combined.ww
 examples/mandelbrot/mandelbrot
 examples/cmatrix/cmatrix
 examples/lisp/lisp