fix(dictionary): handle Hachidori extension load failures gracefully

- Catch errors from the Hachidori extension runtime and log them
- Clear the extension and session state and return null instead of rejecting

src/main.ts

@@ -6620,10 +6620,17 @@ const configuredExternalYomitanProfilePath = yomitanProfilePolicy.externalProfil
 const yomitanExtensionRuntime = createYomitanExtensionRuntime({
   loadYomitanExtensionCore: async (deps) => {
     if (activeDictionaryBackend === 'yomitan') return loadYomitanExtensionCore(deps);
+    try {
       const extension = await hachidoriExtensionRuntime.ensureLoaded();
       deps.setYomitanExtension(extension);
       deps.setYomitanSession(getHachidoriSession());
       return extension;
+    } catch (error) {
+      logger.error('Failed to load Hachidori extension:', error);
+      deps.setYomitanExtension(null);
+      deps.setYomitanSession(null);
+      return null;
+    }
   },
   userDataPath: USER_DATA_PATH,
   externalProfilePath: configuredExternalYomitanProfilePath,