Replace the <details>-based kebab popover with a proper Material-
style navigation drawer:
- Hamburger button (menu icon) at top-left.
- <aside> drawer slides in from the left via transform: translateX().
width: min(85vw, 320px). Backdrop overlay behind it.
- Close paths: X button in the drawer header, backdrop click, Esc.
- Padding honours Android safe-area insets on all four sides.
- Model selector + label live inside the drawer; future per-app
settings can move here too.
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