Save the transcript as subtitles too, not just as text

whisper-1's verbose response carries a start and an end for every segment,
and the file tab was reading only the start, to build the [mm:ss] prefix.
Keeping the end as well is all an SRT needs.

The text stays the authority on wording and the segments on timing; they
meet at that prefix, which the cleanup model is already told to leave alone.
So a transcript that went through cleanup still turns into properly timed
subtitles. A line whose stamp matches no segment runs until the next line
starts, a line with no stamp at all joins the cue above it, and an end that
would run into the next cue is trimmed back.

The button is dead until a timestamped run finishes, because without
timestamps there are no segments to time anything with.

i18n.py

@@ -197,8 +197,15 @@ TR = {
     "Stop": "Durdur",
     "Copy": "Panoya kopyala",
     "Save as .txt": "'.txt' olarak kaydet",
+    "Save as .srt": "'.srt' olarak kaydet",
+    "Subtitles, timed from the segments. Needs the timestamps option.":
+        "Altyazı; zamanlaması bölüm damgalarından gelir. Zaman damgası seçeneği "
+        "işaretliyken çalışır.",
+    "No timestamped lines to turn into subtitles.":
+        "Altyazıya çevrilecek zaman damgalı satır yok.",
     "Save transcript": "Transkripti kaydet",
     "Text files": "Metin dosyaları",
+    "Subtitle files": "Altyazı dosyaları",
     "Converting audio…": "Ses dönüştürülüyor…",
     "Splitting into {count} chunks…": "{count} parçaya bölünüyor…",
     "Transcribing chunk {index}/{count}…": "{index}/{count} parça yazıya çevriliyor…",