Fix streaming content disappearing on window switch and improve skills scanning

- Add useRef + visibilitychange/focus listener to re-sync streaming content
  when Electron window regains focus, preventing blank content flash
- Remove duplicate text SSE events from assistant handler (stream_event
  already provides real-time deltas)
- Make skills scanner recursive to find commands in subdirectories
- Add debug logging for skills directory resolution

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/lib/claude-client.ts

@@ -289,13 +289,10 @@ export function streamClaude(options: ClaudeStreamOptions): ReadableStream<strin
           switch (message.type) {
             case 'assistant': {
               const assistantMsg = message as SDKAssistantMessage;
+              // Text deltas are handled by stream_event for real-time streaming.
+              // Only track lastAssistantText here and process tool_use blocks.
               const text = extractTextFromMessage(assistantMsg);
-              if (text && text !== lastAssistantText) {
-                // Send the new delta
-                const delta = text.slice(lastAssistantText.length);
-                if (delta) {
-                  controller.enqueue(formatSSE({ type: 'text', data: delta }));
-                }
+              if (text) {
                 lastAssistantText = text;
               }