fix: scroll settings list to keep selection in view

[LargeModGames]

Summary

The Settings screen list could not be scrolled past what initially fit on screen. Pressing Down moved the highlight through the visible rows, but the viewport never scrolled to reveal items below the fold, so the lower settings were unreachable on shorter terminals.

• The settings list was the only scrollable list in the app rendered statelessly (f.render_widget). A stateless ratatui List has no scroll offset, so it always draws from item 0 and never follows the selection. The visible highlight is faked by per-item span styling, so it moved on screen, but once the selection passed the viewport bottom the selected row went off-screen with no scroll.
• Fixed by rendering with a ListState seeded from settings_selected_index (f.render_stateful_widget), mirroring discover.rs, util.rs, and every other list screen, so ratatui recomputes the offset each frame to keep the selection visible.

Not actually platform-specific despite being reported on Windows: it only looked fine on Linux because that terminal was tall enough to show all 25 items at once.

Testing

• cargo fmt --all
• cargo clippy --no-default-features --features telemetry -- -D warnings — clean
• cargo test --no-default-features --features telemetry — 233 passed; 0 failed
• Manual: opened Settings, shrank the terminal so items overflow, and confirmed the list now scrolls all the way down to "Announcements Feed URL" and back, keeping the highlighted row in view.

Additional notes

• Stateful rendering activates the already-configured ▶ highlight symbol, so the selected row now shows the ▶ arrow and all rows gain a 2-column left gutter for it. This matches the other list screens; no other layout or logic changes.