[shadowmap] fix: align dashboard styles with slint

[mdabir1203]

Summary

• retain layered background gradients and add positioned radial glows using supported Slint syntax to set the dashboard depth
• restyle stats, activity, and list cards with translucent gradients, borders, and drop shadows for a glassmorphic look
• replace unsupported widget styling with a custom GlassButton and glass-wrapped LineEdit to preserve refined controls within Slint 1.5 constraints

Testing

• cargo check -p shadowmap

---

https://chatgpt.com/codex/tasks/task_e_68f7d332ed1c8326baa4e727928bc030