Add loading splash screen for app startup

**Splash Screen Features:**
- Shows "Local Transcription" branding during startup
- Displays progress messages as app initializes
- Prevents users from clicking multiple times while loading
- Clean dark theme matching app design

**Implementation:**
- Created splash screen with custom pixmap drawing
- Updates messages during initialization phases:
  - "Loading configuration..."
  - "Creating user interface..."
  - "Starting web server..."
  - "Loading Whisper model..."
- Automatically closes when main window is ready
- Always stays on top to remain visible

**Benefits:**
- Better user experience during model loading (2-5 seconds)
- Prevents multiple app instances from confusion
- Professional appearance
- Clear feedback that app is starting

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

main.py

@@ -14,10 +14,53 @@ from pathlib import Path
 project_root = Path(__file__).parent
 sys.path.insert(0, str(project_root))
 
-from PySide6.QtWidgets import QApplication
+from PySide6.QtWidgets import QApplication, QSplashScreen
+from PySide6.QtGui import QPixmap, QPainter, QColor, QFont
+from PySide6.QtCore import Qt, QTimer
 from gui.main_window_qt import MainWindow
 
 
+def create_splash_pixmap(message="Loading..."):
+    """Create a pixmap for the splash screen with a custom message."""
+    pixmap = QPixmap(500, 300)
+    pixmap.fill(QColor("#2b2b2b"))
+
+    # Draw on the pixmap
+    painter = QPainter(pixmap)
+    painter.setRenderHint(QPainter.Antialiasing)
+
+    # Draw title
+    title_font = QFont("Arial", 28, QFont.Bold)
+    painter.setFont(title_font)
+    painter.setPen(QColor("#ffffff"))
+    painter.drawText(pixmap.rect(), Qt.AlignCenter, "Local Transcription")
+
+    # Draw subtitle
+    subtitle_font = QFont("Arial", 12)
+    painter.setFont(subtitle_font)
+    painter.setPen(QColor("#888888"))
+    subtitle_rect = pixmap.rect().adjusted(0, 60, 0, 0)
+    painter.drawText(subtitle_rect, Qt.AlignCenter, message)
+
+    # Draw version/status at bottom
+    status_font = QFont("Arial", 10)
+    painter.setFont(status_font)
+    painter.setPen(QColor("#666666"))
+    status_rect = pixmap.rect().adjusted(0, 0, 0, -20)
+    painter.drawText(status_rect, Qt.AlignHCenter | Qt.AlignBottom, "Please wait...")
+
+    painter.end()
+    return pixmap
+
+
+def create_splash_screen():
+    """Create a splash screen for startup."""
+    pixmap = create_splash_pixmap("Initializing...")
+    splash = QSplashScreen(pixmap)
+    splash.setWindowFlags(Qt.WindowStaysOnTopHint | Qt.SplashScreen)
+    return splash
+
+
 def main():
     """Main application entry point."""
     try:
@@ -31,8 +74,21 @@ def main():
         app.setApplicationName("Local Transcription")
         app.setOrganizationName("LocalTranscription")
 
-        # Create and show main window
-        window = MainWindow()
+        # Create and show splash screen
+        splash = create_splash_screen()
+        splash.show()
+        app.processEvents()  # Make sure splash is visible
+
+        # Update splash with progress
+        splash.showMessage("Loading configuration...", Qt.AlignBottom | Qt.AlignCenter, QColor("#888888"))
+        app.processEvents()
+
+        # Create main window (this takes time due to model loading)
+        # Pass splash to window so it can update the message
+        window = MainWindow(splash_screen=splash)
+
+        # Close splash and show main window
+        splash.finish(window)
         window.show()
 
         # Run application