ClearChat Home v1.3.3 - Explicit Avatar Upload Button

Changes:
- Adds a visible Upload Avatar button directly under the avatar file chooser.
- Keeps Save Settings for normal text/settings changes.
- Upload Avatar saves selected image into uploads/avatars and updates Agent Avatar URL.
- Bumps displayed version to 1.3.3-home.

Upgrade notes:
- Existing config.php and uploaded files are preserved by the updater.
- If uploads fail, confirm /clearchat/uploads/avatars is writable by Apache/PHP.
