test(telegram-tts): add unit tests for summarizeText function

- Export summarizeText in _test for testing
- Add 8 tests covering:
  - Successful summarization with metrics
  - OpenAI API call parameters verification
  - targetLength validation (min/max boundaries)
  - Error handling (API failures, empty responses)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pnpm-lock.yaml

@@ -393,6 +393,8 @@ importers:
 
   extensions/telegram: {}
 
+  extensions/telegram-tts: {}
+
   extensions/tlon:
     dependencies:
       '@urbit/aura':