Fix print preview to show content and improve file loading timing

Print Preview Fixes:
- Fixed print preview to show actual preview content instead of formatting menu
- Changed from generic 'preview' ID to active tab's 'preview-{tabId}' element
- Added CSS positioning to make preview fixed and full-screen during print
- Hide all dialog overlays (export, batch, PDF, converter) during print
- Restore dialogs after print completes
- Enhanced print-mode CSS with z-index and positioning for proper display
File Loading Timing Improvements:
- Increased renderer-ready delay from 500ms to 1000ms for slower first loads
- Increased openFileFromPath delay from 100ms to 300ms
- Ensures UI fully initializes before files are displayed
- Files now render correctly on first double-click launch
🤖 Generated with [Claude Code](https://claude.com/claude-code)

src/styles.css

@@ -2956,6 +2956,17 @@ body.theme-concrete-warm .status-bar {
     display: block !important;
     width: 100% !important;
     max-width: 100% !important;
+    position: fixed !important;
+    top: 0 !important;
+    left: 0 !important;
+    z-index: 9999 !important;
+    background: white !important;
+    padding: 20px !important;
+}
+
+/* Ensure preview panes are visible in print mode */
+#preview-pane-1, #preview-pane-2, #preview-pane-3, #preview-pane-4, #preview-pane-5 {
+    display: block !important;
 }
 
 .print-no-styles .preview-content {