fix(overlay): show plain subtitle line immediately on tokenization cache miss (#184)

changes/subtitle-plain-line-on-cache-miss.md

@@ -0,0 +1,4 @@
+type: fixed
+area: overlay
+
+- Subtitle lines no longer wait for tokenization to finish before appearing, even when the previous line is still being processed. On a tokenization cache miss, the plain line is shown immediately at its cue time and upgrades in place once tokens and annotations are ready; stale results cannot replace newer cues, and the basic plain-text websocket no longer receives a duplicate event for the annotation-only upgrade. A failed tokenization is no longer cached as the plain line, so a repeated line gets another chance at annotations instead of staying plain for the rest of the session.