v4.0.4.15 - Web overhaul + handle sync + updater rename

v4.0.4.15 - Web client overhaul + handle sync + updater rename

Web client (platytalk.platysoft.com/client.html):

• Massively improved readability: brighter text, stronger borders, visible message bubbles (cyan-on-dark for outgoing, navy for incoming), larger fonts, removed marketing-page scanline overlay
• Invite QR card redesigned: prominent "Copy invite link" primary button, full URL displayed and selectable, optional native Share menu on mobile, click QR to enlarge in modal
• Local data wiped status text removed from chat header

Handle sync:

• Server: PUT /v1/me/handle now broadcasts a profileUpdated WebSocket event to every device for the user
• Desktop client: subscribes to the new event and updates the local identity automatically when the handle is changed from the web client (or any other device)
• Web client: other open tabs refresh the identity card and QR when the handle changes

Updater fix for legacy installs:

• The Windows MSI for the Full edition is now named PlatypusToolsFullSetup-vX.Y.Z.msi (was PlatypusToolsSetup-...). Because "Full" sorts before "Media" alphabetically, the buggy v4.0.4.3 auto-updater (which always picked the first MSI it found) will now finally pick the correct Full MSI.
• v4.0.4.12 and later already contain the proper edition-aware MSI selection logic; this rename is a one-time hop for stuck v4.0.4.3 installs.

Server changes deployed to platysoft.com.