Rename binary to agent-orchestrator, add splash screen, fix white flash

- Rename Cargo package from bterminal to agent-orchestrator so WM_CLASS
  matches desktop entry and taskbar groups correctly
- Update lib name (agent_orchestrator_lib) and telemetry service name
- Add Pandora's Box splash screen with progress steps during startup
- Prevent white window flash with inline CSS and Tauri backgroundColor

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

v2/src-tauri/tauri.conf.json

@@ -17,7 +17,8 @@
         "height": 1080,
         "resizable": true,
         "fullscreen": false,
-        "decorations": true
+        "decorations": true,
+        "backgroundColor": [30, 30, 46, 255]
       }
     ],
     "security": {