feat: add version display to CLI banner and WebUI

- Add getPackageVersion() utility function in src/utils/helpers.js
- Display version in CLI startup banner (e.g., "v2.4.2")
- Display version in WebUI navbar next to "CLAUDE PROXY SYSTEM"
- Refactor WebUI to use shared getPackageVersion() utility
- Update footer with GitHub icon and link

package.json

@@ -1,6 +1,6 @@
 {
   "name": "antigravity-claude-proxy",
-  "version": "1.2.6",
+  "version": "2.4.2",
   "description": "Proxy server to use Antigravity's Claude models with Claude Code CLI",
   "main": "src/index.js",
   "type": "module",