Add user-configurable colors for transcription display

- Add color settings (user_color, text_color, background_color) to config
- Add color picker buttons in Settings dialog with alpha support for backgrounds
- Update local web display to use configurable colors
- Send per-user colors with transcriptions to multi-user server
- Update Node.js server to apply per-user colors on display page
- Improve server landing page: replace tech details with display options reference
- Bump version to 1.3.2

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

config/default_config.yaml

@@ -59,6 +59,10 @@ display:
   font_size: 12
   theme: "dark"
   fade_after_seconds: 10  # Time before transcriptions fade out (0 = never fade)
+  # Color settings (used for both local display and server sync)
+  user_color: "#4CAF50"  # User's name color (default green)
+  text_color: "#FFFFFF"  # Text/font color (default white)
+  background_color: "#000000B3"  # Background color with alpha (default semi-transparent black)
 
 web_server:
   port: 8080