Expose explicit LiveSync batching and honour save failures

Show the batching choice for the current synchronisation mode while
preserving both mode preferences. Observe local save failures before
file-open work and report failed asynchronous unload preparation.

Record the accepted recovery and batching contract, update the primary
settings documentation, and add two-device runtime coverage for batching,
deletions, saved settings, and interrupted local processing.

Requires Commonlib commit 72bdc66af5d7338d8f2f69ebe83c3866def93360.
Update the exact registry dependency when its package version is published.

Validation: full repository check; latest packed dependency type checks,
production build, 1,373 unit tests (one skipped), and six focused runtime
recovery cases. The earlier implementation passed the full 23-case runtime
comparison and five additional interruption conditions.

src/main.ts

@@ -1,4 +1,5 @@
 import { useP2PSettingsPreparation } from "@/serviceFeatures/useP2PSettingsPreparation";
+import { LOG_LEVEL_URGENT } from "octagonal-wheels/common/logger";
 import { getLanguage, Notice, Plugin, type App, type PluginManifest } from "./deps";
 import { setGetLanguage } from "@vrtmrz/livesync-commonlib/compat/common/coreEnvFunctions";
 setGetLanguage(getLanguage);
@@ -233,6 +234,12 @@ export default class ObsidianLiveSyncPlugin extends Plugin {
         void this._startUp();
     }
     override onunload(): void {
-        return void this.core.services.control.onUnload();
+        void this.core.services.control.onUnload().catch((error) => {
+            this.core.services.API.addLog(
+                "Failed to unload Self-hosted LiveSync: " + String(error),
+                LOG_LEVEL_URGENT,
+                "shutdown"
+            );
+        });
     }
 }