fix: recover chat state after idle reconnects

Resyncs active sessions after hidden upstream stream reconnects
Recovers orphaned streaming parts with active-session snapshots
Adds coverage for event-stream reconnect behavior

package.json

@@ -110,7 +110,7 @@
     "@ibm/plex": "^6.4.1",
     "@lezer/highlight": "^1.2.3",
     "@octokit/rest": "^22.0.1",
-    "@opencode-ai/sdk": "^1.17.9",
+    "@opencode-ai/sdk": "^1.17.12",
     "@radix-ui/react-collapsible": "^1.1.12",
     "@radix-ui/react-dialog": "^1.1.15",
     "@radix-ui/react-dropdown-menu": "^2.1.16",