0.1.5

Add dex-submit Firefox extension

Auto-submits Dex login device code flow and closes tab on success.

Features:
- User-configurable Dex domains via extension preferences
- Auto-clicks submit button on configured Dex /device pages
- Automatically closes tab after successful login
- Skips submission if login error is present
- Build system with Makefile for signing and releases
- Version syncing across manifest, package.json, and updates.json