feat: add tray support and cross-platform packaging assets (v0.9.6)

- Generate placeholder icons: icon.png (512x512), tray-icon.png (16x16), icon.icns (macOS)
- Fix window close behavior: hide to tray instead of quitting
- Add tray left-click and double-click handlers to restore window
- Add app.dock.hide/show on macOS for proper dock visibility
- Bump version to 0.9.6 in package.json, preload.js, openclaw-manager.js

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "odo",
-  "version": "0.9.5",
+  "version": "0.9.6",
   "description": "ODO — OpenClaw Dashboard Orchestrator",
   "main": "main.js",
   "scripts": {