ci: materialize origin refs as refs/heads before mirror push

actions/checkout fetches origin branches under refs/remotes/origin/*
only. git push --mirror copies every ref to the destination as-is, so
those landed on forge as refs/remotes/origin/* (invisible in the
branches view) and refs/heads/main never made it across — the only
proper branch that did was the one actions/checkout materialized to
run the workflow on (refs/heads/ci/forge-mirror).

Re-fetch with refspec +refs/heads/*:refs/heads/* so the local repo
has the branches under refs/heads, then --mirror pushes them as
real branches. Tags get the same refspec to keep them out of
refs/remotes.

Author: rudyfraser

.github/workflows/tangle.yml

@@ -31,6 +31,12 @@ jobs:
             IdentitiesOnly yes
           EOF
           chmod 600 ~/.ssh/config
-          git fetch --tags origin
+
+          # actions/checkout leaves origin branches under refs/remotes/origin/*
+          # — git push --mirror would copy those as remote-tracking refs on
+          # the destination instead of as proper branches. Materialize them
+          # under refs/heads/* first so the mirror push lands them as real
+          # branches that forge can render.
+          git fetch origin '+refs/heads/*:refs/heads/*' '+refs/tags/*:refs/tags/*'
           git remote add tangled git@knot.blacksky.community:blackskyweb.xyz/rsky
           git push --mirror tangled