feat(telegram): voice tool sends spoken replies as Telegram voice notes

OpenAI gpt-4o-mini-tts (female voice nova by default; TTS_MODEL/TTS_VOICE) renders OGG/Opus,
sent with sendVoice in order with rendered output. Up to 4500 characters per call, split
into 1500-character parts at paragraph/sentence/word boundaries; all parts are synthesized
before any is sent, and API errors come back to the agent as text with the key hidden.
On whenever OPENAI_API_KEY is set.

docker-compose.yml

@@ -23,6 +23,8 @@ services:
       # Optional features; empty means off / default.
       - OPENAI_API_KEY=${OPENAI_API_KEY:-}                  # speech to text (attachments spec)
       - STT_MODEL=${STT_MODEL:-}
+      - TTS_MODEL=${TTS_MODEL:-}
+      - TTS_VOICE=${TTS_VOICE:-}
       - OPENROUTER_API_KEY=${OPENROUTER_API_KEY:-}          # group topic triggers via Jev (group triggers spec)
       - TRIGGER_MODEL=${TRIGGER_MODEL:-}
       - GOOGLE_CLIENT_ID=${GOOGLE_CLIENT_ID:-}              # Google Calendar (calendar spec)