Settings popover can clip on narrow / short windows

[stultus]

Area: src/lib/components/SettingsModal.svelte
Severity: High

Problem

The settings popover is anchored to bottom: 40px; left: 16px with no viewport-edge
clamp. On small windows or high DPI the card can overflow the screen; on short
windows the new tall version scrolls internally but the trigger ends up far away.

Suggested fix

• Add a viewport-edge clamp so the modal never overflows.
• If the card is taller than available space, switch to scrollable with a subtle
  inner scroll indicator.
• Consider using a portal/floating-ui style anchor to the gear button.