feat: add Ollama audio transcription and runtime config reload

- add audio capability reporting for Ollama models
- support Telegram voice messages via ffmpeg conversion and Ollama transcription
- add USE_SYSTEM_PROMPT toggle and runtime reloading of .env/system prompt settings
- support ollama_options.json for custom Ollama request options
- improve Telegram MarkdownV2 escaping and formatting preservation
- add environment setters for AI provider credentials and models
- show audio capability in info/model commands

src/model/ai-model-capabilities.ts

@@ -5,4 +5,5 @@ export class AiModelCapabilities {
     ocr?: AiCapabilityInfo;
     thinking?: AiCapabilityInfo;
     tools?: AiCapabilityInfo;
+    audio?: AiCapabilityInfo;
 }