M3b review fixes by the design model: curl --globoff, podman --pull=never

Review findings 1 and 2, both plan defects. curl gains --globoff and a
leading --disable; both podman runs gain --pull=never. The given fetch.rs and
the six golden files change with them. Checked on straylight with a rebuilt
image: a glob URL is one request, a missing image fails at once.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/brokerd/src/podman.rs

@@ -23,6 +23,9 @@ pub fn container_name(session: &SessionId, call: CallId, n: u64) -> String {
 /// takes the runner's, the proxy its fixed limits.
 fn hardening(pids: u32, memory: &str) -> Vec<OsString> {
     [
+        // A missing image is an error at once, never a pull: a pull is egress, and what runs must
+        // be exactly the image built for it.
+        "--pull=never",
         "--read-only",
         "--cap-drop=all",
         "--security-opt=no-new-privileges",