fix: handle HTTPS redirects in InsecureTlsHelper for OIDC discovery

Java's automatic redirect following creates new connections that do NOT
inherit custom SSLSocketFactory/HostnameVerifier. This caused the OIDC
discovery fetch to fail on redirect even with TLS_SKIP_VERIFY=true.
Now disables auto-redirect and follows manually with SSL on each hop.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/security/InsecureTlsHelper.java

@@ -10,6 +10,8 @@ import javax.net.ssl.SSLSocketFactory;
 import javax.net.ssl.TrustManager;
 import javax.net.ssl.X509TrustManager;
 import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.net.URI;
 import java.net.URL;
 import java.net.URLConnection;
 import java.security.SecureRandom;
@@ -59,13 +61,33 @@ final class InsecureTlsHelper {
     /**
      * Opens an {@link InputStream} from the given URL, applying trust-all TLS
      * if the connection is HTTPS and {@code skipVerify} is true.
+     * <p>
+     * Handles redirects manually because Java's automatic redirect following
+     * creates new connections that do NOT inherit custom SSLSocketFactory /
+     * HostnameVerifier settings.
      */
     static InputStream openStream(URL url, boolean skipVerify) throws Exception {
-        URLConnection conn = url.openConnection();
+        URL current = url;
+        for (int i = 0; i < 5; i++) {
+            HttpURLConnection conn = (HttpURLConnection) current.openConnection();
             if (skipVerify && conn instanceof HttpsURLConnection https) {
                 https.setSSLSocketFactory(socketFactory());
                 https.setHostnameVerifier(hostnameVerifier());
             }
+            conn.setInstanceFollowRedirects(false);
+            int code = conn.getResponseCode();
+            if (code >= 300 && code < 400) {
+                String location = conn.getHeaderField("Location");
+                conn.disconnect();
+                if (location == null) {
+                    throw new java.io.IOException("Redirect with no Location header from " + current);
+                }
+                current = new URI(location).toURL();
+                log.debug("Following OIDC redirect -> {}", current);
+                continue;
+            }
             return conn.getInputStream();
         }
+        throw new java.io.IOException("Too many redirects from " + url);
+    }
 }

cameleer3-server-app/src/main/java/com/cameleer3/server/app/security/OidcTokenExchanger.java

@@ -61,6 +61,9 @@ public class OidcTokenExchanger {
                                SecurityProperties securityProperties) {
         this.configRepository = configRepository;
         this.tlsSkipVerify = securityProperties.isOidcTlsSkipVerify();
+        if (tlsSkipVerify) {
+            log.warn("OIDC TLS skip-verify enabled for token exchanger");
+        }
     }
 
     public record OidcUserInfo(String subject, String email, String name, List<String> roles, String idToken) {}