fix(stats): fix duplicate-line cleanup edge cases

- Drain the full write queue before scanning, not just one batch, so pending burst rows aren't missed
- Floor lookback-days before the positivity check so a sub-day value no longer collapses to a zero-day window
- Let the parsed cue list override the streaming dedup heuristic wherever it covers a line
- Reject combining --lifetime with --duplicate-lines and non-positive --lookback-days values
- Widen the burst frame bound to catch heavier typesetting while still sparing longer-spaced runs
- Keep the cleanup modal open until the user closes it so they can read the result before it unmounts

src/core/services/stats-server/route-support.ts

@@ -98,10 +98,12 @@ export function parseDuplicateLineCleanupBody(body: unknown): {
 } {
   const source = body && typeof body === 'object' ? (body as Record<string, unknown>) : {};
   const rawLookback = source.lookbackDays;
-  const lookbackDays =
-    typeof rawLookback === 'number' && Number.isFinite(rawLookback) && rawLookback > 0
+  // Floor before the bounds check, or a fraction of a day arrives as a zero-day window.
+  const wholeDays =
+    typeof rawLookback === 'number' && Number.isFinite(rawLookback)
       ? Math.floor(rawLookback)
       : null;
+  const lookbackDays = wholeDays !== null && wholeDays >= 1 ? wholeDays : null;
   return { dryRun: source.dryRun === true, lookbackDays };
 }