feat(phase1): rebrand to TTRPG Player and drop Git updates feed

Rename product to TTRPG Player (TTRPGPlayer / com.ttrpgplayer.app), use .ttrpg.zip for new saves while keeping .dnd.zip import, accept TTRPG- and DND- license keys on client, and remove sync-update-feed plus CI push to DndGamePlayerUpdates.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/renderer/boot.html

@@ -113,7 +113,7 @@
     <div class="wrap">
       <div class="card">
         <img class="logo" src="./app-window-icon.png" width="72" height="72" alt="" />
-        <h1 class="title" data-boot-title>DNDGamePlayer</h1>
+        <h1 class="title" data-boot-title>TTRPG Player</h1>
         <p class="subtitle">редактор и проигрыватель</p>
         <p class="version" data-boot-version></p>
         <p class="status" id="boot-status">Запуск…</p>