fix(dub): Timing strategy options never rendered — wrong prop name on Segmented (#313) (#320)

The Timing control passed `options=` to <Segmented>, whose prop is
`items=` (defaulting to []), so the toggle group rendered as a single
empty pill with nothing to click — users had no way to pick
Concise / Stretch Video / Strict slot. Broken since the control was
introduced; every other Segmented call site already uses `items=`.

Closes #313

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

frontend/src/pages/DubTab.jsx

@@ -942,7 +942,7 @@ export default function DubTab(props) {
                   <Segmented
                     value={timingStrategy}
                     onChange={setTimingStrategy}
-                    options={[
+                    items={[
                       { value: 'concise',       label: 'Concise',        title: 'Translator trims text to fit at natural rate. Overflows surface in the row badge so you can shorten the segment.' },
                       { value: 'stretch_video', label: 'Stretch Video',  title: 'Audio plays at natural rate; each segment of the video is stretched (per-segment ffmpeg setpts) to fit. Total video duration grows. Requires a re-encode pass.' },
                       { value: 'strict_slot',   label: 'Strict slot',    title: 'Legacy: compress audio to fit the original timing. Can sound rushed/chipmunky on high-density target languages.' },