setup --check: distinguish a missing rc worktree from no rc branch yet

--check warned 'rc worktree would be created' whenever the directory was
absent, implying a plain setup run would create it — but with no rc branch in
existence setup skips it, so the warning described something that would not
happen and asked for action that was not possible. It now reports the branch
state: present, would-create (branch exists), or nothing-to-do (no branch
yet — the first RC cut creates the branch and the build trigger creates the
worktree on demand). Branch detection is read-only, as --check must be.

bin/setup

@@ -201,11 +201,23 @@ echo ""
 # together.
 RC_WORKTREE="/root/omarchy-pkgs-rc"
 
+# Read-only: --check must not fetch. Local refs first, then a network peek.
+rc_branch_exists() {
+  git -C "$BUILD_ROOT" show-ref --verify --quiet refs/heads/rc && return 0
+  git -C "$BUILD_ROOT" show-ref --verify --quiet refs/remotes/origin/rc && return 0
+  git -C "$BUILD_ROOT" ls-remote --exit-code --heads origin rc >/dev/null 2>&1
+}
+
 if [[ "$CHECK_ONLY" == true ]]; then
   if [[ -d "$RC_WORKTREE" ]]; then
     print_success "rc worktree present: $RC_WORKTREE"
-  else
+  elif rc_branch_exists; then
     print_warning "rc worktree would be created at $RC_WORKTREE"
+  else
+    # Expected before the first RC: nothing to create, and nothing to do —
+    # omarchy-release creates the branch and the rc build trigger creates the
+    # worktree on demand, so this resolves itself.
+    print_info "rc worktree not needed yet (no rc branch — created on the first RC cut)"
   fi
 elif [[ -d "$RC_WORKTREE" ]]; then
   print_success "rc worktree present: $RC_WORKTREE"
@@ -217,9 +229,8 @@ else
   elif git -C "$BUILD_ROOT" show-ref --verify --quiet refs/remotes/origin/rc; then
     git -C "$BUILD_ROOT" worktree add --track -b rc "$RC_WORKTREE" origin/rc
   else
-    print_warning "No rc branch exists yet — skipping worktree"
+    print_info "No rc branch yet — the first RC cut creates it, and the rc build"
-    echo "    The release orchestrator creates the rc branch on the first RC cut;"
+    echo "    trigger creates this worktree on demand. Nothing to do."
-    echo "    re-run bin/setup afterwards."
   fi
 fi
 echo ""