fix: honor Telegram typing indicator setting

[marcoleejr]

Summary

• honor the existing typing_indicator display setting before starting background typing loops
• gate direct Telegram typing calls and progress/follow-up typing pings on the same setting
• add regression coverage for disabled Telegram typing indicators in both the base gateway flow and direct Telegram adapter calls

Testing

• python -m pytest tests/gateway/test_base_topic_sessions.py tests/gateway/test_display_config.py tests/gateway/test_telegram_thread_fallback.py -q

[teknium1]

Superseded by #55394 (merged to main, commit 05ac167). That PR adds a generic per-platform typing_indicator flag at the shared _keep_typing spawn site, covering Telegram and every other platform via typing_indicator: false. Thanks for the contribution — credited in the merged PR.