feat(launcher): complete Campaign LA11 pre-gate support

src/AcDream.Launcher.Core/Updates/ReleaseManifestClient.cs

@@ -11,8 +11,9 @@ public interface IReleaseManifestClient
 
 /// <summary>
 /// Strict, bounded reader for the pinned GitHub Releases manifest. Production
-/// construction is HTTPS-only. The loopback HTTP allowance is available only
-/// through an internal fixture factory and is never inferred from a URI.
+/// construction is pinned and HTTPS-only. The explicitly named process-local
+/// feed factory independently revalidates its URI and can admit HTTP only for
+/// the loopback operator fixture; it cannot change the production constructor.
 /// Redirects are followed manually so every hop is checked before any bytes
 /// cross that hop.
 /// </summary>
@@ -74,6 +75,49 @@ public sealed class ReleaseManifestClient : IReleaseManifestClient, IDisposable
             CreateRedirectDisabledHandler(),
             timeout);
 
+    /// <summary>
+    /// Creates the explicit process-local feed seam used by the Campaign LA
+    /// isolated operator fixture. HTTPS stays HTTPS-only. HTTP is admitted
+    /// only for a loopback manifest, and never by the pinned production
+    /// constructor. Credential-bearing or mutable URI suffixes are rejected.
+    /// </summary>
+    public static ReleaseManifestClient CreateLocalUpdateFeedOverride(
+        Uri manifestUri,
+        TimeSpan? timeout = null)
+    {
+        ArgumentNullException.ThrowIfNull(manifestUri);
+        if (!string.IsNullOrEmpty(manifestUri.UserInfo)
+            || !string.IsNullOrEmpty(manifestUri.Query)
+            || !string.IsNullOrEmpty(manifestUri.Fragment))
+        {
+            throw new LauncherUpdateException(
+                "A process-local manifest URI cannot contain user information, "
+                + "a query, or a fragment.");
+        }
+
+        bool allowLoopbackHttp = string.Equals(
+                manifestUri.Scheme,
+                Uri.UriSchemeHttp,
+                StringComparison.Ordinal)
+            && manifestUri.IsLoopback;
+        if (!string.Equals(
+                manifestUri.Scheme,
+                Uri.UriSchemeHttps,
+                StringComparison.Ordinal)
+            && !allowLoopbackHttp)
+        {
+            throw new LauncherUpdateException(
+                "A process-local manifest URI must use HTTPS "
+                + "(loopback HTTP is fixture-only).");
+        }
+
+        return new ReleaseManifestClient(
+            manifestUri,
+            allowLoopbackHttp,
+            CreateRedirectDisabledHandler(),
+            timeout);
+    }
+
     internal static ReleaseManifestClient CreateForTransportTest(
         Uri manifestUri,
         bool allowLoopbackHttp,