Screenshots from the Rust build; system-roots feature for macOS cross-builds

docs/guide/img is re-shot from the 0.6 binary. TLS roots come from the
operating system by default; build.sh cross-builds macOS on Linux without
that feature (no Apple SDK), trusting the bundled Mozilla roots. Lock
tests wait for the reader to report it is blocked rather than assuming
how long unlocking takes on a busy machine.

Co-Authored-By: Claude <noreply@anthropic.com>

src/net/mod.rs

@@ -135,9 +135,14 @@ impl Client {
                 Some(p) => Some(ureq::Proxy::new(p).map_err(|_| "invalid proxy setting in the environment".to_string())?),
                 None => None,
             };
-            let tls = ureq::tls::TlsConfig::builder()
-                .root_certs(ureq::tls::RootCerts::PlatformVerifier)
-                .build();
+            // The operating system's trust store; builds without the
+            // `system-roots` feature (macOS binaries cross-built without
+            // Apple's SDK) use the bundled Mozilla roots instead.
+            #[cfg(feature = "system-roots")]
+            let roots = ureq::tls::RootCerts::PlatformVerifier;
+            #[cfg(not(feature = "system-roots"))]
+            let roots = ureq::tls::RootCerts::WebPki;
+            let tls = ureq::tls::TlsConfig::builder().root_certs(roots).build();
             let l = &self.limits;
             let cfg = ureq::Agent::config_builder()
                 .tls_config(tls)