Merge master into dev/4.11.x and preserve plugin runner architecture

Reconcile migration branches without rewriting published revisions; retain additive Codex, monitoring, provider and platform fixes. Keep dynamic runner schemas and Host ownership, restore compatibility regressions, and preserve safe model-test error handling.

src/langbot/pkg/utils/version.py

@@ -83,7 +83,7 @@ class VersionManager:
         try:
             if await self.is_new_version_available():
                 return (
-                    'New version available. Update guide: https://link.langbot.app/en/docs/update',
+                    'New version available. Update guide: https://langbot.app/docs/en/deploy/update',
                     logging.INFO,
                 )
         except Exception as e: