fix(audio_generator): clean up temp file when gTTS save() fails

[jiawenlai1109]

Problem

generate_audio_cross_platform() creates a temporary MP3 in the current working
directory and removes it in a finally block — but tts.save() is called before
the try, so any exception raised by the save itself escapes the cleanup:

temp_mp3_path = f"temp_audio_{uuid.uuid4().hex}.mp3"
tts.save(temp_mp3_path)          # file is already on disk here

try:
    with open(temp_mp3_path, "rb") as f:
        audio_bytes = f.read()
finally:
    if os.path.exists(temp_mp3_path):
        os.remove(temp_mp3_path)

gTTS.save() performs an outbound HTTP request, so this is exactly the path that fails
when the suite runs offline or behind egress restrictions — and the repo's .gitignore
does not cover temp_audio_*, so every run leaves untracked temp_audio_<hex>.mp3
files in the working tree.

generate_audio_mac_wav() immediately above already handles this correctly: its
finally cleans up both temp paths with per-file error handling. This change makes
generate_audio_cross_platform() consistent with the pattern already used in this file.

Change

One statement moved inside the existing try. No behaviour change on the success path.

     tts = gTTS(text=prompt, lang="en")
     temp_mp3_path = f"temp_audio_{uuid.uuid4().hex}.mp3"
-    tts.save(temp_mp3_path)
-
     try:
+        tts.save(temp_mp3_path)
         with open(temp_mp3_path, "rb") as f:
             audio_bytes = f.read()
     finally:

Evidence

Ubuntu 22.04, Python 3.14.7, test run with no route to the Google TTS endpoint:

run	test result	temp_audio_*.mp3 left in CWD
before	1 failed (gTTSError: Failed to connect)	1
after	1 failed (same gTTSError)	0

black --check on the file: unchanged. Rest of the module: 1 passed, 1 skipped, 1 failed
(the failure is the pre-existing offline one, identical before and after).

Not changed in this PR

test_generate_audio_cross_platform depends on outbound network, so it fails in any
offline sandbox. I left it alone deliberately — happy to add an offline guard in a
separate commit if you want that behaviour decided.

---

[msoedov]

@jiawenlai1109 thx a lot for the patch!