feat: add manual known-word cache refresh path

- Add CLI command flag  with non-GUI dispatch flow and OSD error handling.

- Add runtime integration call and IPC hook so manual refresh works from command runner without app startup.

- Add public AnkiIntegration manual refresh API with force refresh semantics and guard reuse.

- Preserve default n+1 behavior by fixing config validation for malformed  values and adding tests.

src/main.ts

@@ -704,6 +704,7 @@ function handleCliCommand(
     startPendingMineSentenceMultiple: (timeoutMs: number) =>
       startPendingMineSentenceMultiple(timeoutMs),
     updateLastCardFromClipboard: () => updateLastCardFromClipboard(),
+    refreshKnownWordCache: () => refreshKnownWordCache(),
     triggerFieldGrouping: () => triggerFieldGrouping(),
     triggerSubsyncFromConfig: () => triggerSubsyncFromConfig(),
     markLastCardAsAudioCard: () => markLastCardAsAudioCard(),
@@ -1110,6 +1111,14 @@ async function updateLastCardFromClipboard(): Promise<void> {
   );
 }
 
+async function refreshKnownWordCache(): Promise<void> {
+  if (!appState.ankiIntegration) {
+    throw new Error("AnkiConnect integration not enabled");
+  }
+
+  await appState.ankiIntegration.refreshKnownWordCache();
+}
+
 async function triggerFieldGrouping(): Promise<void> {
   await triggerFieldGroupingService(
     {